EP1622507A2

EP1622507A2 - Methods and device for non-invasive analyte measurement

Info

Publication number: EP1622507A2
Application number: EP04760590A
Authority: EP
Inventors: John F. Burd; William Sell; Jacob Fraden; Charles E. Kramer; Gary Krantz; Bart Chapman
Original assignee: Oculir Inc
Current assignee: JOHN F. BURD
Priority date: 2003-05-02
Filing date: 2004-04-27
Publication date: 2006-02-08
Also published as: WO2004099824A3; JP2006525084A; WO2004099824A2

Abstract

The present invention is related to non-invasive methods and instruments to detect the level of analyte concentrations in the tissue of a subject. The spectra of mid-infrared radiation emitted from a subject's body are altered corresponding to the concentration of various compounds within the radiating tissue. In one aspect of the invention, an instrument(200) floods a body surface of the subject, such as the subject's eye (100), with radiation in the mid-infrared range (150) and measures analyte concentrations based on mid-infrared radiation reflected back to the instrument (200).

Description

TITLE OF THE INVENTION

METHODS AND DEVICE FOR NON-INVASIVE ANALYTE MEASUREMENT

FIELD OF THE INVENTION [0001] The present invention is related to optical non-invasive methods and instruments to detect the presence or measure the concentration of a wide range of analytes, such as glucose, in the tissue of a subject. The spectra of mid-infrared radiation emitted from the subject's body are altered corresponding to the presence, absence or concentration of the analyte within the subject's tissue, one aspect of the present invention, the instrument floods a surface of the subject's body, such as the skin or eye, any orifice, piercing tract or cavity such as the mouth, ear or nose, with light in the mid-infrared range and determines an analyte's presence, absence or concentration based on said analyte's distinctive mid- infrared radiation signature reflected back to the instrument. In another aspect of the invention, an instrument measures the level of mid-infrared radiation from a surface of the subject's body, including but not limited to mid-infrared radiation emitted from any body surface, such as the skin or the eye, any orifice, piercing tract, or cavity, such as the mouth, ear or nose, and determines a specific analyte's presence or concentration based on said analyte's distinctive mid-infrared radiation signature. In a a preferred embodiment, the present invention is related to non-invasive methods to detect the presence or measure the concentration of a wide range of analytes, such as glucose, in the conjunctiva of a subject. The spectra of mid-infrared radiation emitted or reflected from the subject's conjunctiva are altered corresponding to the presence, absence or concentration of the analyte within the subject's conjunctiva. In one aspect of the present invention, the conjunctiva of the subject's eye is utilized as a source of an optical signal to determine an analyte's presence, absence or concentration based on said analyte's distinctive spectral characteristics detected by an instrument capable of detecting the optical signal. The measurements made by the instrument, on the conjunctiva or any other body part, of the present invention do not require direct contact of the instrument with a surface of a subject's body. BACKGROUND OF THE INVENTION

[0002] Diabetes remains one of the most serious and under-treated diseases facing the worldwide healthcare system. Diabetes is a chronic disease where the body fails to maintain normal levels of glucose in the bloodstream. It is now the fifth leading.cause of death from disease in the U.S. today and accounts for about 15% of the entire healthcare budget. People with diabetes are classified into two groups: Type 1 (formerly known as "juvenile onset" or "insulin dependent" diabetes, that are required to take insulin to maintain life) and Type 2 (formerly known as "adult onset" or "non-insulin dependent," that may require insulin but may sometimes be treated by diet and oral hypoglycemic drugs). In both cases, without dedicated and regular blood glucose measurement, all patients face the possibility of the complications of diabetes that include cardiovascular disease, kidney failure, blindness, amputation of limbs and premature death.

[0003] The number of cases of diabetes in the U.S. has jumped 40% in the last decade. This high rate of growth is believed to be due to a combination of genetic and lifestyle origins that appear to be a long-term trend, including obesity and poor diet. The American Diabetes Association (ADA) and others estimate that about 17 million Americans and over 150 million people worldwide have diabetes, and it is estimated that up to 40% of these people are currently undiagnosed. American Diabetes Association, "Facts & Figures."

[0004] Diabetes must be "controlled" in order to delay the onset of the disease complications. Therefore, it is essential for people with diabetes to measure their blood glucose levels several times per day in an attempt to keep their glucose levels within the normal range (80 to 130 mg/dL). These glucose measurements are used to determine the amount of insulin or alternative treatments necessary to bring the glucose level to within target limits. Self-Monitoring of Blood Glucose (SMBG) is an ongoing process repeated multiple times per day for the rest of the patient's lifetime.

[0005] All currently FDA approved invasive or "less-invasive" (blood taken from the arm or other non-fingertip site) glucose monitoring products currently on the market require the drawing of blood in order to make a quantitative measurement of blood glucose. The ongoing and frequent measurement requirements (1 to possibly 10 times per day) presents all diabetic patients with pain, skin trauma, inconvenience, and infection risk resulting in a general reluctance to frequently perform the critical measurements necessary for selecting the appropriate insulin dose or other therapy.

[0006] These current product drawbacks have led to a poor rate of patient compliance. Among Type 1 diabetics, 39% measure their glucose levels less than once per day and 21% do not monitor their glucose at all. Among Type 2 diabetics who take insulin, only 26% monitor at least once per day and 47% do not monitor at all. Over 75% of non- ■ insulin-taking Type 2 diabetics never monitor their glucose levels. Roper Starch Worldwide Survey. Of 1,186 diabetics surveyed, 91% showed interest in a non-invasive glucose monitor, [www. childrenwithdiabetes . com] As such, there is both a tremendous interest and clinical need for a non-invasive glucose sensor.

[0007] A preferred embodiment of the present invention seeks to replace the currently used blood glucose measurement methods, devices and instruments, including invasive measures and the use of glucose test strips, with an optical non-invasive instrument.

[0008] Various methods have been developed related to non-invasive glucose sensing using a dermal testing site such as the finger or earlobe. These methods primarily employ instruments which measure blood-glucose concentration by generating and measuring light only in the near-infrared radiation spectrum. For example, U.S. Patent No. 4,882,492 (the '492 patent) is directed to an instrument which transmits near-infrared radiation through a sample to be tested on the skin surface of a human. In the '492 patent, the near- infrared radiation that passes through the sample is split into two beams, wherein one beam is directed through a negative correlation filter and the second through a neutral density filter. The differential light intensity measured through the filters of the two light beams is proportional to glucose concentration according to the '492 patent.

[0009] U.S. Patent No. 5,086,229 (the '229 patent) is directed to an instrument which generates near-infrared radiation within the spectrum of about 600 to about 1100 nanometers. According to the '229 patent, a person places their finger in between the generated near-infrared radiation source and a detector, which correlates the blood-glucose concentration based on the detected near-infrared radiation. Similarly, U.S. Patent No. 5,321,265 (the '265 patent) also measures blood-glucose level using both near-infrared radiation and the fingertip as a testing site. The detectors disclosed in the '265 patent further comprise silicon photocells and broad bandpass filters.

[0010] U.S. Patent No. 5,361,758 (the '758 patent) is directed to an instrument which measures near-infrared radiation that is either transmitted through or is reflected from the finger or earlobe of a human. In the '758 patent, the transmitted or reflected light is separated by a grating or prism, and the near-infrared radiation is detected and correlated with blood-glucose concentration. This instrument of the '758 patent also comprises an additional timing and control program wherein the device takes measurements specifically in between heartbeats and can also adjust for temperature.

[0011] U.S. Patent No. 5,910,109 (the '109 patent) is also directed to an instrument for measuring blood-glucose concentration using near-infrared radiation and the earlobe as the testing site. The instrument of the '109 patent comprises four light sources of a very specific near-infrared emission spectrum, and four detectors having specific near-infrared detection spectra corresponding to the wavelength of the light sources. The signals detected by the four distinct detectors are averaged, and these averages are analyzed to determine blood-glucose concentration according to the '109 patent.

[0012] The technique of using near-infrared radiation, wherein the near-infrared radiation is transmitted through or reflected from a dermal testing site and monitored for measuring glucose in vivo, is known to be inaccurate. The glucose concentration of interest is in the blood or the interstitial fluid, not on the surface of the dermis. Therefore these methods must penetrate down into the layers beneath the top layers of dermis. There are a number of substances in the dermis that can interfere with the near-infrared glucose signal. Additionally, there is a wide variation in the human dermis, both between individuals and within a given individual. Moreover, glucose simply lacks a satisfactory distinguishable "fingerprint" in the near-infrared radiation spectrum. Because near-infrared radiation is not sufficiently adsorbed by glucose and because of the level of tissue interferences found in the dermis, this technique is substantially less desirable for the accurate measurement of blood-glucose concentrations.

[0013] U.S. Patent No. 6,362,144 (the '144 patent) discloses using the fingertip as a testing site, however, the described instrument uses attenuated total reflection (ATR) infrared spectroscopy. According to the '144 patent, a selected skin surface, preferably the finger, is contacted with an ATR plate while ideally maintaining the pressure of contact. In the '144 patent, the skin is then irradiated with a mid-infrared beam, wherein said infrared radiation is detected and quantified to measure blood-glucose levels. This technique is not ideal, however, if the surface of tissue from which the measurement is taken is very dense in the wavelength region of interest or is not amenable to direct contact with the ATR plate, such as an eye, nose, mouth, or other orifice, cavity or piercing tract.

[0014] The minimal depth of peripheral capillaries in epithelial tissues is typically about 40 microns. Again, there are physical characteristics as well as a number of substances present in the skin that can interfere with the desired glucose-specific signal. While useful in the laboratory, both the near-infrared transmission methods, and the ATR method mentioned above are not practical, or may not be adequate for use in monitoring blood glucose concentration in patients.

[0015] Methods have also been developed related to non-invasive glucose sensing using the eye as a testing site. For example, in both U.S. Patent Nos. 3,958,560 (the '560 patent) and 4,014,321 (the '321 patent) a device utilizing the optical rotation of polarized light is described. In the '560 and the '321 patents, the light source and light detector are incorporated into a contact lens which is placed on the surface of the eye whereby the eye is scanned using a dual source of polarized radiation, each source transmitting in a different absorption spectrum at one side of the cornea or aqueous humor. The optical rotation of the radiation that passes through the cornea correlates with the glucose concentration in the cornea according to the '560 and '321 patents. While this method would be termed, "non-invasive," because the withdrawal of blood is not required, it may still cause significant discomfort or distort vision of the user because of the need to place the sensor directly on the eye. [0016] U.S. Patent No. 5,009,230 (the '230 patent) uses a polarized light beam of near- infrared radiation within the range of 940 to 1000 nm. In the '230 patent, the amount of rotation imparted by glucose present in the bloodstream of the eye on the polarized light beam is measured to determine glucose concentration. Again, the accuracy is limited because glucose simply lacks a sufficiently distinguishable "fingerprint" in this near- infrared radiation spectrum.

[0017] Both U.S. Patent No. 5,209,231 (the '231 patent), and International Publication No. WO 92/07511 (the '511 application) similarly disclose the use of polarized light, which is initially split by a beam splitter into a reference beam and a detector beam, and then transmitted through a specimen, preferably the aqueous humor of the eye. The amount of phase shift as compared between the transmitted reference and detector beams are correlated to determine glucose concentration in the '231 patent and '511 application. U.S. Patent No. 5,535,743 (the '743 patent) measures diffusely reflected light provided by the surface of the iris as opposed to the aqueous humor of the eye. According to the '743 patent, the measurement of optical absorption is possible whereas measurement of the optical rotation through the aqueous humor is not possible. hi the '743 patent, the intensity of the diffusely reflected light, however, may be analyzed to obtain useful information on the optical properties of the aqueous humor, including blood-glucose concentration.

[0018] U.S. Patent No. 5,687,721 (the '721 patent) also discloses a method of measuring blood-glucose concentration by generating both a measurement and reference polarized light beam, and comparing said beams to determine the angle of rotation, which is attributable to the blood-glucose concentration. The preferable testing site disclosed, however, is the finger or other suitable appendage according to the '721 patent. The '721 patent further discloses and requires the use of a monochromatic laser and/or semiconductor as a light source.

[0019] U.S. Patent No. 5,788,632 (the '632 patent) discloses a non-invasive instrument for determining blood-glucose concentration by transmitting a first beam of light through a first polarizer and a first retarder, then directing the light through the sample to be measured, transmitting the light through a second polarizer or retarder, and lastly detecting the light from the second detector. The rotation of measured polarized light is correlated to the blood-glucose concentration of the sample measured according to the '632 patent.

[0020] U.S. Patent No. 5,433,197 (the '197 patent) discloses a non-invasive instrument for determining blood-glucose concentration using a broad-band of near-infrared radiation which illuminates the eye in such a manner that the energy passes through the aqueous humor in the anterior chamber of the eye and is then reflected from the iris. The reflected energy then passes back through the aqueous humor and the cornea and is collected for spectral analysis. According to the '197 patent, the electrical signals representative of the reflected energy are analyzed by univariate and/or multivariate signal processing techniques to correct for any errors in the glucose determination. Again, the accuracy of the instrument in the '197 patent is limited because glucose simply lacks a sufficiently distinguishable "fingerprint" in this near-infrared radiation spectrum.

[0021] Instruments and methods of using the body's naturally emitted radiation to measure blood-glucose concentration using the human body, and in particular, the tympanic membrane as a testing site have also been disclosed. U.S. Patent Nos. 4,790,324; 4,797,840; 4,932,789; 5,024,533; 5,167,235; 5,169,235; and 5,178,464 describe various designs, stabilization techniques and calibration techniques for tympanic non-contact thermometers, h addition, U.S. Patent No. 5,666,956 (the '956 patent) discloses an instrument which measures electromagnetic radiation from the tympanic membrane and computes monochromatic emissivity using Plank's law by measuring the radiation intensity, spectral distribution, and blackbody temperature. According to the '956 patent, the resultant monochromatic emissivity is variable depending on the spectral characteristics of the site measured, namely the blood-glucose concentration measured from the tympanic membrane. It should be noted, however, that the '956 patent equates skin surfaces of the body to a "gray-body" rather than a black-body with respect to its monochromatic emissivity. Therefore, according to the '956 patent, the accuracy of such skin surface-based methods utilizing natural black-body emitted radiation is not useful for analyte measurements, as compared to a method of subsurface analysis utilizing natural black-body radiation emitted from the tympanic membrane.

[0022] The human body naturally emits from its surfaces infrared radiation whose spectrum, or radiation signature, is modified by the presence, absence or concentration of analytes in the body tissues. The eye is particularly well suited as a testing site to detect this infrared radiation. For example, certain analytes, such as glucose, exhibit a minimal time delay in glucose concentration changes between the eye and the blood, and the eye provides a body surface with few interferences. Cameron et al., (3)2 DIABETES TECHNOL. THER., 202-207 (2001). There is, therefore, in the field of non-invasive blood analyte monitoring, an unmet need for a suitable instrument, and methodologies for using it, to accurately measure analyte concentrations, such as blood glucose concentration, as well as concentrations of other desired analytes, in subjects requiring this type of blood analyte measurement.

SUMMARY OF THE INVENTION

[0023] The present invention is related to non-invasive methods and instruments to detect the presence of an analyte, or the level of analyte concentrations, in the tissue of a subject either by flooding a body surface with infrared radiation and measuring the reflected infrared radiation or by using the subject's natural black-body radiation and analyzing the emitted radiation to determine the analyte concentration. The instruments and methods of the present invention do not require direct contact of the instrument with a surface of a subject's body in order to make the analyte measurements. A body surface that is particularly well suited for such measurements is the conjunctiva. The conjunctiva covers the exposed surface of the eye, with the exception of the cornea. The conjunctiva is a clear, thin layer of tissue that lies over the white part of the eye and also lines the inside of the eyelids. The conjunctiva helps keep the eyelids and eyeball moist, and has other functions important for the eye. The conjunctiva is highly vascularized, and the interstitial fluid contained within the conjunctiva has been found to provide an excellent site for the non-invasive measurement of blood or tissue analytes, including glucose. Non-invasive methods of the present invention include, but are not limited to, electromagnetic radiation and any other optical signal measurement. [0024] hi a preferred embodiment, the analyte that is actually measured or detected may be any compound or substance that has a radiation signature in the mid-infrared range. In addition to directly measuring the presence, absence or concentration of a particular analyte, the methods and instrument of the present invention may also be used to detect the presence, absence or concentration of any compound or substance that represents a surrogate marker for or has a correlation to the presence, absence, or concentration of another analyte of interest, including but not limited to any metabolite or degradation product of an analyte, or an upstream or downstream pathway component or product that is affected by an analyte of interest. In this situation the analyte that is actually measured is a surrogate marker for another analyte of interest. The methods and instrument of the present invention may also be utilized to detect the presence, absence or concentration of analytes in air that has been contacted with or exhaled by a subject. Such airborne analytes may be, for example, any volatile compound or substance including but not limited to ketones, beta hydroxybutyrate, or alcohols.

[0025] Another embodiment of the present invention relates to a method for measuring an analyte concentration in a tissue of a subject which may comprise exposing the eye of the subject to mid-infrared radiation, determining the reflected mid-infrared radiation spectrum and determining the analyte concentration in the tissue. In this embodiment, the subject being tested may be a mammal, and preferably the subject is a human. Further, the analyte concentration being measured may be any analyte having a detectable radiation signature. In one embodiment, the analyte concentration being measured is glucose concentration. In another embodiment, the analyte concentration may be measured for a wide variety of tissues of a subj ect' s body.

[0026] h another embodiment, the present invention relates to an instrument which measures the level of mid-infrared radiation from a surface of a subject's body and determines a specific analyte's concentration based on the analyte's distinctive mid- infrared radiation signature. The instrument in this embodiment may optionally further comprise a light source capable of generating mid-infrared radiation and a mid-infrared radiation detector. In another embodiment, the instrument may also comprise a microprocessor and a display. In one embodiment, the instrument comprises a light source which may be any suitable mid-infrared light source, including, but not limited to, broad band or narrow band light emitting diodes, a Nernst glower, a NiChrome wire, and a Globar. In another embodiment, the instrument may also comprise a wavelength selector which may further comprise a filter of any suitable type, including but not limited to, an absorption filter, interference filter, monochro ator, linear variable filter, circular variable filter, and a prism, hi another embodiment, the instrument may also comprise a mid- infrared light detector, which may be any suitable type, including, but not limited to a thermocouple, a thermistor, a microbolometer, and a liquid nitrogen cooled MTC.

[0027] In another embodiment, the present invention relates to an instrument which floods a surface of a subject's body with light comprising light in the mid-infrared range and measures analyte concentrations based on a mid-infrared radiation signature of the analyte reflected back to the instrument. In this embodiment, the instrument further comprises a light source capable of generating mid-infrared radiation having wavelengths in the range of about 2.5 microns to about 25.0 microns, a mid-infrared radiation detector capable of detecting mid-infrared radiation having wavelengths in the range of about 8.0 microns to about 11.0 microns, and optionally comprising a microprocessor, and a display, hi one embodiment, the instrument further comprises a light source which may be any suitable mid-infrared producing light source, including, but not limited to, broad band or narrow band light emitting diodes, a Nernst glower, a NiChrome wire, and a Globar. In addition, the instrument of this embodiment may optionally further comprise a selector which itself may further comprise a suitable wavelength filter, including, but not limited to, an absorption filter, interference filter, monochromator, linear variable filter, circular variable filter, and a prism. In one embodiment, the instrument may also comprise a suitable mid- infrared light detector, including, but not limited to, a thermocouple, a thermistor, a microbolometer, and a liquid nitrogen cooled MTC.

[0028] In another embodiment of the present invention, the instrument may comprise a display, such as an alphanumeric display, including, but not limited to, a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED), h another embodiment of the present invention, the instrument comprises an audio display which may be provided with an audio source comprising recorded audio clips, speech synthesizers and voice emulation algorithms to audibly report the analyte concentration.

[0029] h another embodiment, the instrument of the present invention comprises a microprocessor and a memory which is operatively linked to the microprocessor. The instrument of this embodiment may also further comprise a communications interface adapted to transmit data from the instrument to a computer system, hi this embodiment, the communications interface selected may be any suitable interface, including, but not limited to, a serial, parallel, universal serial bus (USB), FireWire, Ethernet, fiber optic, co- axial, and twisted pair cables.

[0030] In another embodiment, the present invention relates to a computer system for downloading and storing measured analyte concentrations. This embodiment may further comprise a computer processor, a memory which is operatively linked to the computer processor, a communications interface adapted to receive and send data within the computer processor, and a computer program stored in the memory which executes in the computer processor. The computer processor of this embodiment further comprises a database, wherein data received by the processor may be stored on the memory as a database, and sorted into predetermined fields, and the database may be capable of graphical representations of the downloaded analyte concentrations. The graphical representations of this embodiment may include, but are not limited to, column, line, bar, pie, XY scatter, area, radar, and surface representations.

[0031] In another embodiment, the present invention relates to a computer interface which is further adapted to transmit data for analyte concentrations to a remote computer processor or user. In this embodiment, a remote user may be physicians, research institutes, specialists, nurses, hospice service providers, insurance carriers, and health care providers.

[0032] In a further embodiment, the present invention relates to a method or system for downloading and storing a subject's analyte concentrations which may comprise measuring the analyte concentration using a non-invasive instrument having a communications interface, connecting the non-invasive instrument through the communications interface to a computer system having a computer processor, a computer program which executes in the computer processor, and an analogous communications interface, and downloading the measured analyte concentrations from the non-invasive instrument to the computer system. The communications interface of this embodiment further comprises a communications interface adapted to transmit data from the instrument to a computer system. In this embodiment, the communications interface may include, for example, serial, parallel, universal serial bus (USB), FireWire, Ethernet, fiber optic, co-axial, and twisted pair cables.

[0033] Other objectives, features and advantages of the present invention will become apparent from the following detailed description. The detailed description and the specific examples, although indicating specific embodiments of the invention, are provided by way of illustration only. Accordingly, the present invention also includes those various changes and modifications within the spirit and scope of the invention that may become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1, Panels A and B: Provides a graphical illustration of the human eye in Panel A showing the conjunctiva. Panel B shows the high degree of vascularization in the conjunctiva, with veins (V) and arterioles (A).

[0035] Figure 2: Provides a chart that depicts the mid-infrared radiation spectral fingerprint for glucose.

[0036] Figure 3: Provides a graphical illustration of one embodiment of the present invention, wherein analyte concentration is measured from the mid- infrared radiation reflected back from the eye.

[0037] Figure 4: Provides a graphical illustration of one embodiment of the present invention, wherein analyte concentration is measured from the mid- infrared radiation naturally emitted from the eye. [0038] Figure 5: Provides a flowchart of one embodiment of the present invention, comprising a method wherein a remote access user can receive a subject's measured analyte concentrations which have been downloaded and stored in a computer system.

[0039] Figure 6: Provides a graph of multiple dose response measurements using detection of varying concentrations of aqueous glucose solutions using polyethylene membranes as the measurement surface.

[0040] Figure 7: Shows a plot of the glucose concentration versus mid- infrared absorption using polyethylene membranes as the measurement surface

[0041] Figure 8: Shows a plot of the results obtained from mid-infrared measurements of glucose concentration using rabbit eye as the surface from which the measurements were made.

[0042] Figure 9: Shows a plot of human data obtained from the surface of the patient's eye measured using mid-infrared absorption to determine blood glucose concentration of the patient.

[0043] Figure 10: Shows a plot of the data obtained from a human diabetic patient in a glucose tracking study demonstrating a correlation of glucose concentration with mid-infrared absorption measured from the human eye surface.

DETAILED DESCRIPTION OF THE INVENTION

[0044] It is understood that the present invention is not limited to the particular methodologies, protocols, instruments, and systems, etc., described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a mid-infrared filter" is a reference to one or more filters and includes equivalents thereof known to those skilled in the art, and so forth.

[0045] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Preferred methods, devices, and materials are described, although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.

DEFINITIONS

[0046] Analyte: As used herein describes any particular substance to be measured. Analyte may also include any substance in the tissue of a subject, or is present in air that was in contact with or exhaled by a subject, which demonstrates and infrared radiation signature. Examples of analytes include, but are not limited to, metabolic compounds or substances, carbohydrates such as sugars including glucose, _^proteins, peptides, or amino acids, fats or fatty acids, triglycerides, polysaccharides, alcohols including ethanol, toxins, hormones, vitamins, bacteria-related substances, fungus-related substances, virus-related substances, parasite-related substances, pharmaceutical or non-pharmaceutical compounds, substances, pro-drugs or drugs, and any precursor, metabolite, degradation product or surrogate marker of any of the foregoing. Analyte may also include any substance which is foreign to or not normally present in the body of the subject.

[0047] Conjunctiva: As used herein describes the membranous tissue that covers the exposed surface of the eye and the inner surface of the eyelids. [0048] Far-Infrared Radiation: As used herein refers to any radiation, either generated from any source or naturally emitted, having wavelengths of about 50.00 to about 1000.00 microns.

[0049] Flooding: As used herein refers to broadly applying relatively widely diffused or spread-out rays of light onto a surface.

[0050] Focused: As used herein means mostly parallel rays of light that are caused to converge on a specific predetermined point.

[0051] Infrared Radiation: As used herein refers to any radiation, either generated from any source or naturally emitted, having wavelengths of about 0.78 to about 1000.00 microns.

[0052] Mid-Infrared Radiation: As used herein refers to any radiation, either generated from any source or naturally emitted, having wavelengths of about 2.50 microns to about 50.00 microns.

[0053] Mid-Infrared Radiation Detector: As used herein refers to any detector or sensor capable of registering infrared radiation. Examples of a suitable infrared radiation detectors, include but are not limited to, a thermocouple, a thermistor, a microbolometer, and a liquid nitrogen cooled MTC. The combined detected infrared radiation may be correlated with wavelengths corresponding to analyte concentrations using means such as the Fourier transform to produce high resolution spectra.

[0054] Near-Infrared Radiation: As used herein refers to any radiation, either generated or naturally emitted, having wavelengths of about 0.78 to about 2.50 microns.

[0055] Surface: As used herein refers to any part of a subject's body that may be exposed to the external environment, including but not limited to, skin, the eye, ear, mouth, nose or any other orifice, body cavities, piercing tracts or other surface whether naturally occurring or artificial such as a surgically created surface.

[0056] Tissue: As used herein includes any tissue or component of a subject, including, but not limited to, skin, blood, body fluids, the eye, the tear layer of the eye, interstitial fluid, ocular fluid, bone, muscle, epithelium, fat, hair, fascia, organs, cartilage, tendons, ligaments, and any mucous membrane.

NON-INVASIVE GLUCOSE MEASUREMENT [0057] In one aspect of the present invention, mid-infrared radiation is flooded onto a body surface using a radiation source. This flooded mid-infrared radiation is reflected from the body surface to a detector. The reflected radiation is detected by a mid-infrared detection instrument placed before the body surface. Again, the radiation signature of the reflected mid-infrared radiation is affected by the presence or concentration of analytes. This provides a non-invasive method employing an instrument of the present invention to measure analyte presence, absence or concentration, such as glucose, from any body surface, including the eye, of a subject (Figure 3).

[0058] In another aspect of the current invention, human beings are natural emitters or radiators of energy in the mid-infrared radiation spectrum. In one aspect of the present invention, the body acts as its own light (or heat) source, providing the mid-infrared radiation signature of the analytes present therein, hi this aspect, and with respect to the surfaces of a subject's body, light (or heat) from the body is emitted or radiated from a body surface, and is detected by a mid-infrared detection instrument. The mid-infrared radiation signature in the body's mid-infrared radiation emission is affected by the presence, absence or concentration of analytes, such as glucose, in the tissues of a subject.

The natural mid-infrared radiation signature of glucose contained within the body's natural mid-infrared radiation signature provides the basis for a non-invasive glucose measurement method and instruments for making such measurements (Figure 3). In addition, decreasing or increasing the concentration of certain analytes may cause an increase in the body's natural emission of infrared radiation. Such an increase in the body's natural infrared radiation emission may provide a measurable signal that may be utilized to measure the presence, absence or concentration of an analyte.

[0059] There is substantial evidence that fluctuations in blood glucose levels are well correlated with glucose levels in the aqueous humor of the eye. (Steffes, 1(2) DIABETES TECHNOL. THER., 129-133 (1999)). hi fact, it is estimated that the time delay between the blood and aqueous humor glucose concentration averages only about five minutes. (Cameron et al., 3(2) DIABETES TECHNOL. THER., 201-207 (2001)). The aqueous humor is a watery liquid that lies between the lens and cornea, which bathes and supplies the nutrients to the cornea, lens and iris (Figure 1). The glucose in the eye is located throughout the various components and compartments of the eye, including, but not limited to, epithelial cells, the aqueous humor, the vitreous humor, various layers of the cornea, iris, various layers of the sclera, conjunctiva, tears, the tear layer, and blood vessels. Therefore, the eye, including, but not limited to, the tear layer, is both an ideal and suitable body surface for non-invasive measurement of the presence, absence or concentration of analytes in the tissue of a subject.

MEASURING MID-INFRARED RADIATION

[0060] When electromagnetic radiation is passed through a substance, it can either be absorbed or transmitted, depending upon its frequency and the structure of the molecules it encounters. Electromagnetic radiation is energy and hence when a molecule absorbs radiation it gains energy as it undergoes a quantum transition from one energy state

(Einitiai) to another (Efϊ_naι). The frequency of the absorbed radiation is related to the energy of the transition by Planck's law: Efi„_aι - Ej_njtj_aι = E = hn = hc/1 . Thus, if a transition exists which is related to the frequency of the incident radiation by Planck's constant, then the radiation can be absorbed. Conversely, if the frequency does not satisfy the Planck expression, then the radiation will be transmitted. A plot of the frequency of the incident radiation vs. some measure of the percent radiation absorbed by the sample is the radiation signature of the compound. The absorption of some amount of the radiation that is applied to a substance, or body surface containing substances, that absorbs radiation may result in a measurable decrease in the amount of radiation energy that actually passes through, or is affected by, the radiation absorbing substances. Such a decrease in the amount of radiation that passes through, or is affected by, the radiation absorbing substances may provide a measurable signal that may be utilized to measure the presence, absence or the concentration of an analyte.

[0061] The human body emits electromagnetic radiation within the infrared radiation spectrum. The spectral characteristics of the infrared radiation emitted can be correlated with the properties of the emitting object, such as a subject's body surface. For example, glucose absorbs mid-infrared radiation at wavelengths between about 8.0 microns to about 11.0 microns. If mid-infrared radiation passes through or reflects from an object where glucose is present, a distinct radiation "fingerprint" or "signature" can be detected from the remaining light that is not absorbed, creating a radiation signature. The radiation signature created can both confirm the presence or absence of an analyte and indicate the concentration of an analyte. In addition, since glucose is a radiation absorbing substance, there may be a measurable decrease in the amount of radiation energy that passes through or reflects from a glucose containing material such as the body surfaces of a subject, including the subject's eye. This measurable decrease in the amount of radiation energy may be utilized to measure the presence, absence or concentration of glucose in a subject.

[0062] One embodiment of the present invention provides a method for non-invasively measuring the blood-analyte concentration in a subject comprising the steps of generating mid-infrared radiation which is flooded onto a body surface of the subject, detecting the reflected mid-infrared radiation, coreelating the spectral characteristics of the detected mid-infrared radiation with a radiation signature that corresponds to the analyte concentration, and analyzing the detected mid-infrared radiation signature to give an analyte concentration measurement. In another embodiment, the method includes a filtering step before detection, by filtering the mid-infrared radiation reflected back from a body surface so that only wavelengths of about 8.00 microns to about 11.00 pass through the filter. In this embodiment, the filtering step may be accomplished using absorption filters, interference filters, monochromators, linear or circular variable filters, prisms or any other functional equivalent known in the art. The detecting step may be accomplished using any mid-infrared radiation sensor such as a thermocouple, thermistor, microbolometer, liquid nitrogen cooled MTC, or any other functional equivalent known in the art. Correlating the spectral characteristics of the detected mid-infrared radiation may comprise the use of a microprocessor to correlate the detected mid-infrared radiation signature with a radiation signature of an analyte. If the analyte being measured is glucose, then the radiation signature generated may be within the wavelength range within about 8.0 to about 11.0 microns. The analyzing step further comprises a microprocessor using algorithms based on Plank's law to conelate the absorption spectrum with a glucose concentration, i another embodiment of the present invention, the analyzing step may comprise the use of a transform, such as, but not limited to, Kramers-Kronig transform or other classical transform known in the art, to transform the detected mid-infrared signal to the analyte spectra for conelation.

[0063] h another embodiment of the present invention, where glucose in the analyte of interest, an instrument comprising a mid-infrared radiation detector and a display may be held up to a body surface of a subject. The infrared radiation from the body surface may optionally be filtered so that only wavelengths of about 8.0 microns to about 11.0 microns reach the mid-infrared radiation detector. The radiation signature of the mid-infrared radiation detected by the detector may then be conelated with a radiation signature that corresponds to a glucose concentration. The radiation signature may then be analyzed to give an accurate glucose concentration measurement. The measured glucose concentration may be displayed.

[0064] hi another embodiment of the present invention, an instrument comprising a mid- infrared radiation generator, a mid-infrared radiation detector and a display may be held up to a body surface of a subject. Mid-infrared radiation may be generated by the instrument and used for flooding or alternatively aiming a focused beam onto a body surface of a subject. The mid-infrared radiation generated may be broad band or narrow band radiation, and may also be filtered to allow only desired wavelengths of radiation to reach the body surface. Any analyte, such as glucose, present in any constituent of the body surface may absorb some of the generated radiation. The mid-infrared radiation that is not absorbed may be reflected back to the instrument. The reflected mid-infrared radiation may optionally be filtered so that only wavelengths of about 8.0 microns to about 11.0 microns reach the mid-infrared radiation detector. The radiation signature of the mid-infrared radiation detected by the detector may then be correlated with a radiation signature that corresponds to analyte, such as glucose, concentration. The radiation signature may be analyzed to give analyte, such as glucose, concentration. The measured analyte, such as glucose, concentration may be displayed by the instrument.

[0065] Infrared radiation may be generated by the instrument of the present invention. Such infrared radiation may be generated by a narrow band wavelength generator or a broad band wavelength generator. In one embodiment of the present invention, an instrument may comprise a mid-infrared radiation generator. In another embodiment of the present invention, the instrument comprises a light source with one or more filters to restrict the wavelengths of the light reaching the body surface. The mid-infrared generator may further comprise a heating element. The heating element of this embodiment may be a Nernst glower (zirconium oxide/yttrium oxides), a NiChrome wire (nickel-chromium wire), and a Globar (silicon-carbon rod), narrow band or broad band light emitting diodes, or any other functional equivalent known in the art. Mid-infrared radiation has wavelengths in the range of about 2.5 microns to about 50.0 microns. Analytes typically have a characteristic "fingerprint" or "signature" with respect to its mid-infrared radiation spectrum that results from the analyte's affect on the mid-infrared radiation, such as absorption. Glucose in particular has a distinct spectral "fingerprint" or "signature" in the mid-infrared radiation spectrum, at wavelengths between about 8.0 microns to about 11.0 microns. This radiation signature of glucose may be readily generated for a wide variety of glucose concentrations utilizing a wide variety of body surfaces for taking radiation signature data. In one embodiment of the present invention, an instrument may comprise a mid-infrared radiation filter, for filtering out all mid- infrared radiation not within a range of wavelengths from about 8.0 to about 11.0 microns, h other embodiments the filter is selected to filter out all mid-infrared radiation other than other than the wavelengths that provide the radiation signature of the desired analyte, such as glucose. Filtering mid-infrared radiation may be accomplished using absorption filters, interference filters, monochromators, linear or circular variable filters, prisms or any other functional equivalent known in the art. [0066] The instrument of the present invention may also comprise a mid-infrared radiation detector for detecting mid-infrared radiation. The mid-infrared radiation detector can measure the naturally emitted or reflected mid-infrared radiation in any form, including in the form of heat energy. Detecting the naturally emitted or reflected mid-infrared radiation may be accomplished using thermocouples, thermistors, microbolometers, liquid nitrogen cooled MTC, or any other functional equivalent known in the art. Both thermocouples and thermistors are well known in the art and are commercially available. For example, thermocouples are commonly used temperature sensors because they are relatively inexpensive, interchangeable, have standard connectors and can measure a wide range of temperatures, hi addition, Thermometrics product portfolio comprises a wide range of thermistors (thermally sensitive resistors) which have, according to type, a negative (NTC), or positive (PTC) resistance/temperature coefficient.

[0067] The instrument of the present invention may also comprise a microprocessor. The microprocessor of this embodiment correlates the detected mid-infrared radiation with a radiation signature whose spectral characteristics provide information to the microprocessor about the analyte concentration being measured. The microprocessor of this embodiment analyzes the resultant radiation signature using algorithms based on Plank's law to translate the radiation signature into an accurate analyte concentration measurement in the sample being measured.

[0068] It is readily apparent to those skilled in the art that a broad band light source may be modulated by an interferometer, such as in Fourier transform spectroscopy, or by an electro-optical or moving mask, as in Hadamard transform spectroscopy, to encode wavelength information in the time domain. A discrete wavelength band may be selected and scanned in center wavelength using, for example, an acousto-optical tuned filter. The instrument of the present invention having a radiation source, comprises one or more mid- infrared radiation sources, which provide radiation at many wavelengths, and also comprises one or more mid-infrared radiation detector. The instrument may further comprise one or more filter or wavelength selector to remove, distinguish or select radiation of a desired wavelength, before or after detection by the detector. CLINICAL APPLICATIONS

[0069] It may be required for diabetes patients and subjects at risk for diabetes to measure their blood glucose levels regularly in an attempt to keep their blood glucose levels within an acceptable range, and to make an accurate recordation of blood-glucose levels for both personal and medical records. In one aspect of the present invention, the instrument may also comprise an alphanumeric display for displaying the measured blood-glucose concentration. The alphanumeric display of this embodiment may comprise a visual display and an audio display. The visual display may be a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED) or any other functional equivalent known in the art. An audio display, capable of transmitting alphanumeric data and converting this alphanumeric data to an audio display, may be provided with an audio source comprising recorded audio clips, speech synthesizers and voice emulation algorithms or any other functional equivalent known in the art.

[0070] Self-Monitoring of Blood Glucose (SMBG) is an ongoing process repeated multiple times per day for the rest of the diabetic patient's lifetime. Accurate recordation of these measurements are crucial for diagnostic purposes. A facile storage and access system for this data is also contemplated in this invention, h one aspect of the present invention, an instrument for non-invasively measuring blood-glucose concentration further comprises a microprocessor and a memory which is operatively linked to the microprocessor for storing the blood glucose measurements. The instrument of this embodiment further comprises a communications interface adapted to transmit data from the instrument to a computer system. In this embodiment the communications interface selected may include, for example, serial, parallel, universal serial bus (USB), Fire Wire, Ethernet, fiber optic, co-axial, and twisted pair cables or any other functional equivalent known in the art.

[0071] In addition to storing blood-glucose measurement data within an instrument, the present invention includes a computer system for downloading and storing these measurement data to facilitate storage and access to this information. The present invention further contemplates a computer processor, a memory which is operatively linked to the computer processor, a communications interface adapted to receive and send data within the computer processor, and a computer program stored in the memory which executes in the computer processor. The computer program of this embodiment further comprises a database, wherein data received by the database may be sorted into predetermined fields, and the database may be capable of graphical representations of the downloaded analyte concentrations. The graphical representations of this embodiment may include, but are not limited to, column, line, bar, pie, XY scatter, area, radar, and surface representations.

[0072] The computer system contemplated by the present invention should be accessible to a remote access user via an analogous communications interface for use as a diagnostic, research, or other medically related tool. Physicians, for example, could logon to the computer system via their analogous communications interface and upload a patient's blood-glucose measurements over any period of time. This information could provide a physician with an accurate record to use as a patient monitoring or diagnostic tool such as, for example, adjusting medication levels or recommending dietary changes. Other remote access users contemplated may include research institutes, clinical trial centers, specialists, nurses, hospice service providers, insurance carriers, and any other health care provider.

[0073] The present invention has demonstrated that glucose can be non-invasively measured using a mid-infrared signal from a body surface. Studies have been performed in a variety of systems, in vitro studies using glucose solutions on membrane samples, in vivo rabbit studies with varying blood glucose concentrations, and human studies with a diabetic human volunteer with varying blood glucose concentrations. These studies have used different types of infrared detector heads for taking the infrared measurements.

[0074] The inventors of the present invention have found that mid-infrared radiation (in the 8 to 12 micron wavelength range) was unable to penetrate through the cornea (which is about 500 microns thick) and into the aqueous humor. The inventors of the present invention have also found that mid-infrared radiation did penetrate the conjunctiva, and that glucose measurements obtained using mid-infrared radiation from the conjunctiva provided a dose response curve that conelated very well to blood glucose measurements using standard SMBG testing strips. [0075] All studies, including the human studies, clearly demonstrate the dose-response to glucose concentrations using mid-infrared measurement techniques.

EXAMPLES

[0076] The following examples are provided to describe and illustrate the present invention. As such, they should not be construed to limit the scope of the invention. Those in the art will well appreciate that many other embodiments also fall within the scope of the invention, as it is described hereinabove and in the claims.

EXAMPLE 1

Experimental In- Vitro Model to Test Precision and Accuracy of the Instrument

Instrumentation

[0077] The instrument used for the Mid-infrared measurements was the SOC 400 portable FTIR. The SOC 400 portable FTIR is based on an interferometer and was originally designed for the US Army to detect battlefield gases. This instrument has been modified to allow measurements on rabbit and human eyes. These modifications have included the installation of a filter to allow only energy in the 7 to 13 micron region to be measured and also the modification of the faceplate to permit easier placement of the instrument for rabbit and human studies.

h Vitro Studies

[0078] Studies were performed to demonstrate that solutions with varying concentrations of glucose would give a Mid-infrared dose-response. Hydrophilic polyethylene membranes from Milhpore Corporation were saturated with glucose solutions with concentrations at 2000 mg/dL and lower. The series of curves generated in this experiment are shown in Figure 4. For this plot, the following equation was used: Absorption = -In (sample spectrum/gold reference spectrum). When the glucose concentration is plotted against the absorption at 9.75 microns, the plot shown in Figure 6 was observed. These studies confirmed that glucose concentration can be measured in an aqueous environment in the mid-infrared wavelength range. EXAMPLE 2 Experimental Rabbit Model

Ketamine Anesthetized Rabbit studies

[0079] As noted in the scientific literature (Cameron et al., DIABETES TECH. THER., (1999) 1(2):135-143), rabbits anesthetized with Ketamine experience a rapid and marked increase in blood glucose concentration, due to the release of glucose from the liver. We have confirmed this in a series of experiments and observed that the rabbit blood sugar can change from -125 mg/dL to -325 mg/dL in 60 minutes, as measured with a LXN ExpressView blood glucose meter. These experiments require a preliminary use of gas anesthesia (Isoflorane) prior to the use of Ketamine. The rabbit was immobilized such that after anesthesia, the eyeball was available for measurements with the SOC 400 portable FTIR. Once the animal was unconscious, a drop of blood from a vein was taken and tested on a blood glucose test strip with the LXN ExpressView blood glucose meter. Such samples were taken every fifteen minutes throughout the study. The gas must be discontinued in order for the Ketamine effect to fully manifest itself. The drying out of the eye may be prevented by suturing the eyelids and using the sutures to open the eye for the measurement and then allowing them to close after the measurement to moisten the eyeball.

[0080] The data from the rabbit study measuring glucose concentration from the sclera yielded the results with a regression coefficient (R squared) of 0.86, shown in Figure 8.

EXAMPLE 3 Human Clinical Study

Human Studies

[0081] Several studies were performed with non-diabetic and diabetic human volunteers. Prior to performing these studies it was confirmed that the infrared radiation being used poses no health hazard.

[0082] Several experiments with a diabetic volunteer were performed. The subject was asked to adjust his food intake and insulin administration in order to have his glucose levels move from approximately 100 to 300 mg/dL over a three to four hour timeframe. During the study, the patient took duplicate fingerstick glucose measurements every ten to fifteen minutes and was scanned with the SOC 400 approximately every fifteen minutes. Prior to collecting the infrared scan, the instrument operator aligned the SOC 400 with the subjects' eye to attempt to collect the strongest signal being reflected off of the eye.

Human Study using the SOC 400 Diffuse detector

[0083] A glucose tracking study was performed using the diffuse detector for the SOC 400 (all previous experiments were performed using the Specular detector). A glucose tracking study was performed with a diabetic volunteer and the results shown in Figure 9 demonstrate that the glucose concentration changes were clearly detected and measured using an instrument and method of the present invention.

EXAMPLE 4 A Method Wherein a Remote Access User Can Receive a Subject's Measured

Analyte Concentrations Which Have Been Downloaded and Stored in a Computer System

[0084] One aspect of the present invention relates to a method of downloading and storing a subject's measured analyte concentrations (Figure 5). A subject first measures the analyte concentration from a body surface such as their eye (100), whereby reflected mid- infrared radiation (150) is measured using a non-invasive instrument (200). The non- invasive instrument (200) further comprises a communications interface (250) which is capable of connecting (300) the non-invasive instrument (200) through the communications interface (250) to a computer system (400). The communications interface (250) is specifically adapted to transmit data from the instrument to the computer system (400). The computer system (400) comprises a computer processor, a computer program which executes in the computer processor, and an analogous communications interface (450). The measured analyte concentrations from the non-invasive instrument (200) are downloaded via the communications interface (250) to the computer system (400). A remote access user (500), having a computer system with an analogous communications interface (450) is capable of retrieving the downloaded measured analyte concentrations from the computer system (400). The communications interfaces (250, 450) may include, for example, serial, parallel, universal serial bus (USB), FireWire, Ethernet, fiber optic, co-axial, and twisted pair cables. This information is used, for example, to provide data, warnings, advice or assistance to the patient or physician, and to track a patient's progress throughout the course of the disease.

Claims

WHAT IS CLAIMED IS:

1. A method comprising the steps: a. using a subject's natural mid-infrared radiation or exposing a body surface of a subject to mid-infrared radiation; b. detecting mid-infrared radiation emitted or reflected from said body surface; and, c. determining a radiation signature of said reflected mid-infrared radiation to determine an analyte concentration in a tissue of said subject.

2. The method of claim 1, wherein said method is non-invasive and wherein said subject is a human.

3. The method of claims 1 or 2, wherein said analyte is selected from the group consisting of metabolic compounds or substances, carbohydrates, sugars, glucose, proteins, peptides, amino acids, fats, fatty acids, triglycerides, polysaccharides, alcohols, ethanol, toxins, hormones, vitamins, bacteria-related substances, fungus- related substances, virus-related substances, parasite-related substances, pharmaceutical compounds, non-pharmaceutical compounds, pro-drugs, drugs, and any precursor, metabolite, degradation product or sunogate marker.

4. The method of any of claims 1 -3 , wherein said analyte is glucose.

5. The method of any of claims 1-4, wherein said tissue is selected from the group consisting of skin, blood, body fluids, eye, interstitial fluid, ocular fluid, bone, muscle, epithelium, fat, hair, fascia, organs, cartilage, tendons, ligaments, and mucous membrane.

6. The method of any of claims 1 -5 , wherein the mid-infrared radiation of step a) is in a wavelength range of about 2.5 microns to about 25.0 microns.

7. The method of any of claims 1-6, wherein said detecting step further comprises selecting and detecting said mid-infrared radiation.

8. The method of any of claims 1-7, wherein said selecting of said emitted or reflected mid-infrared radiation further comprises filtering said reflected mid- infrared radiation.

9. The method of any of claims 1-8, wherein said detecting step and said determining steps further comprise using a microprocessor.

10. The method of any of claims 1-9, wherein said emitted or reflected mid-infrared radiation comprises infrared radiation having wavelengths between about 2.5 microns to about 25.0 microns.

11. The method of any of claims 1-10, wherein said emitted or reflected mid-infrared radiation is within the wavelengths between about 2.5 microns to about 11.0 microns.

12. A method comprising the steps: a. detecting naturally occurring mid-infrared radiation emitted from a subject using a non-invasive instrument comprising a mid-infrared detector; b. comparing a radiation signature of said mid-infrared radiation to a radiation signature of mid-infrared radiation corresponding to an analyte concentration; and c. analyzing said radiation signature of said mid-infrared radiation from said subject to determine said analyte concentration in a tissue of said subject.

13. The method of claim 12, wherein said analyte is selected from the group consisting of metabolic compounds or substances, carbohydrates, sugars, glucose, proteins, peptides, amino acids, fats, fatty acids, triglycerides, polysaccharides, alcohols, ethanol, toxins, hormones, vitamins, bacteria-related substances, fungus-related substances, parasite-related substances, pharmaceutical compounds, non- pharmaceutical compounds, pro-drugs, drugs, and any precursor, metabolite, degradation product or sunogate marker.

14. The method of claims 12 or 13, wherein said analyte is glucose.

15. The method of any of claims 12-14, wherein said tissue is selected from the group consisting of skin, blood, body fluids, eye, tear layer of an eye, interstitial fluid, ocular fluid, bone, muscle, epithelium, fat, hair, fascia, organs, cartilage, tendons, ligaments, and mucous membrane.

16. The method of any of claims 12-15, wherein said tissue is blood.

17. The method of any of claims 12-16, wherein said naturally occurring mid-infrared radiation comprises infrared radiation having wavelengths between about 2.5 microns and about 25.0 microns.

18. The method of any of claims 12-17, wherein said detecting step further comprises selecting and detecting desired wavelengths of said naturally occurring mid- infrared radiation.

19. The method of any of claims 12-18, wherein said comparing step and said analyzing step further comprise using a microprocessor.

20. An instrument comprising: a. a radiation source capable of generating mid-infrared radiation; b. a mid-infrared radiation wavelength detector for detecting said generated mid-infrared radiation reflected from a surface of a subject's body; and, c. a display for alphanumeric or audio representations of an analyte concentration in a tissue of said subject.

21. The instrument of claim 20, further comprising a microprocessor for conelating said detected mid-infrared radiation with wavelengths conesponding to said analyte concentration and analyzing said wavelengths to calculate said analyte concentration in said tissue.

22. The instrument of claims 20 or 21, wherein said mid-infrared radiation detector is selected from the group consisting of a thermocouple, a thermistor, a microbolometer, and liquid nitrogen cooled MTC.

23. The instrument of any of claims 20-22, wherein said mid-infrared radiation wavelength detector, further comprises a mid-infrared radiation selector.

24. The instrument of claim 23, wherein said selector further comprises a filter which is selected from the group consisting of absorption filters, interference filters, monochromators, linear and circular variable filters, and prisms.

25. The instrument of any of claims 20-24, wherein said display is an alphanumeric representation selected from the group consisting of a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED) [add any additional display types].

26. The instrument of any of claims 20-25, wherein said display is an audio display comprising speakers.

27. The instrument of claim 26, wherein said audio display is provided with an audio source selected from a group consisting of recorded audio clips, speech synthesizers and voice emulation algorithms.

28. The instrument of any of claims 20-27, wherein said instrument further comprises an infrared spectrometer.

29. The instrument of any of claims 20-28, wherein said microprocessor further comprises a memory which is operatively coupled to said microprocessor.

30. The instrument of any of claims 20-29, wherein said instrument further comprises a communications interface, wherein said interface is selected from the group consisting of serial, parallel, USB (universal serial bus), FireWire, Ethernet, fiber optic, co-axial, and twisted pair; cables.

31. An instrument comprising : a. a radiation source of mid-infrared radiation within the range of about 2.5 to about 25.0 microns; and b. a mid-infrared radiation detector for detecting said mid-infrared radiation transmitted through a tissue of a subject within a wavelength range of between about 8.0 to about 11.0 microns.

32. The instrument of claim 31, further comprising a microprocessor for conelating said transmitted mid-infrared radiation with a radiation signature conesponding to an analyte concentration and analyzing said radiation signature to calculate said analyte concentration in said tissue of said subject.

33. The instrument of claims 31 or 32, wherein said mid-infrared radiation detector is selected from the group consisting of a thermocouple, a thermistor, a microbolometer, and liquid nitrogen cooled MTC.

34. The instrument of any of claims 31-33, wherein said mid-infrared radiation detector further comprises a mid-infrared radiation selector.

35. The instrument of claim 34, wherein said selector further comprises a filter which is selected from the group consisting of absorption filters, interference filters, monochromators, linear and circular variable filters, and prisms.

36. The instrument of any of claims 31-35, further comprising a display selected from the group consisting of a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED) [add more display types].

37. The instrument of claim 36, wherein said display is an audio display comprising speakers.

38. The instrument of claim 37, wherein said audio display is provided with an audio source selected from a group consisting of recorded audio clips, speech synthesizers and voice emulation algorithms.

39. The instrument of any of claims 31-38, wherein said instrument further comprises an infrared spectrometer.

40. The instrument of any of claims 31-39, wherein said microprocessor further comprises a memory which is operatively coupled to said microprocessor.

41. The instrument of any of claims 31-40, wherein said instrument further comprises a communications interface adapted to transmit data from said instrument to a computer system.

42. The instrument of claim 41, wherein said communications interface is selected from the group consisting of standard input/output, serial cable, parallel cable,

USB (universal serial bus), FireWire, networking card, fiber optic, wireless, coaxial cables, and twisted pair cables.

43. A computer system for downloading and storing data, collected from an instrument according to claim 20 or 31, comprising: a. a computer processor; b. a memory which is operatively coupled to said computer processor; c. a communications interface adapted to receive and send data within said computer processor; and d. a computer program stored in said memory which executes in said computer processor.

44. A method of downloading and storing a subject's measured analyte concentration, comprising the steps of: a. measuring said analyte concentration using a non-invasive instrument of claim 20 or 31 having a communications interface; b. connecting said non-invasive instrument through said communications interface to a computer system having a computer processor, a computer program which executes in said computer processor, and an analogous communications interface; and c. downloading from said non-invasive instrument to said computer system said measured analyte concentrations.

45. A method comprising the steps: a. exposing at least a portion of a conjunctiva surface of a subject to electromagnetic radiation; b. detecting electromagnetic radiation reflected from said conjunctiva; and, c. determining a radiation signature of said reflected electromagnetic radiation to determine an analyte concentration in a tissue of said subject.

46. The method of Claim 45, wherein said method is non-invasive and wherein said subject is a human.

47. The method of Claims 45 or 46, wherein said analyte is selected from the group consisting of metabolic compounds or substances, carbohydrates, sugars, glucose, proteins, peptides, amino acids, fats, fatty acids, triglycerides, polysaccharides, alcohols, ethanol, toxins, hormones, vitamins, bacteria-related substances, fungus- related substances, virus-related substances, parasite-related substances, pharmaceutical compounds, non-pharmaceutical compounds, pro-drugs, drugs, and any precursor, metabolite, degradation product or sunogate marker.

48. The method of any of Claims 45-47, wherein said analyte is glucose.

49. The method of any of Claims 45-48, wherein said electromagnetic radiation is mid- infrared radiation.

50. The method of Claim 49, wherein the mid-infrared radiation is in a wavelength range of about 2.5 microns to about 25.0 microns.

51. The method of any of Claims 45-50, wherein said detecting step further comprises selecting at least one wavelength within said reflected electromagnetic radiation.

52. The method of Claim 51, wherein said selecting of said reflected electromagnetic radiation further comprises filtering said reflected electromagnetic radiation.

53. The method of any of Claims 45-52, wherein said determining step further comprises using a microprocessor.

54. The method of any of Claims 45-53, wherein said reflected electromagnetic radiation comprises infrared radiation having a wavelength range between about

2.5 microns to about 25.0 microns.

55. The method of Claim 54, wherein said reflected infrared radiation is within the wavelength range between about 2.5 microns to about 11.0 microns.

56. A computer system for downloading and storing data collected according to Claim 45, comprising: a. a computer processor; b. a memory which is operatively coupled to said computer processor; c. a communications interface adapted to receive and send data within said computer processor; and d. a computer program stored in said memory which executes in said computer processor.

57. A method of downloading and storing a subject's measured analyte concentration, comprising the steps of: a. measuring said analyte concentration according to the method of Claim 45 using a non-invasive instrument having a communications interface; b. connecting said non-invasive instrument through said communications interface to a computer system having a computer processor, a computer program which executes in said computer processor, and an analogous communications interface; and c. downloading from said non-invasive instrument to said computer system said measured analyte concentrations.