JP2017023508A - Organism characteristic value measurement method and measurement device using near infrared spectrometry - Google Patents
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- 238000000691 measurement method Methods 0.000 title claims description 8
- 238000001320 near-infrared absorption spectroscopy Methods 0.000 title 1
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- 210000004369 blood Anatomy 0.000 claims description 46
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 27
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- 238000004497 NIR spectroscopy Methods 0.000 claims description 15
- 238000004364 calculation method Methods 0.000 claims description 10
- 238000004611 spectroscopical analysis Methods 0.000 claims 1
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- 235000020824 obesity Nutrition 0.000 description 3
- 230000002265 prevention Effects 0.000 description 3
- 230000036760 body temperature Effects 0.000 description 2
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- 230000002641 glycemic effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
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- 239000004366 Glucose oxidase Substances 0.000 description 1
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Abstract
Description
本発明は、近赤外分光法を用いて血糖値などの生体特性値を測定する方法及び装置に関するものである。 The present invention relates to a method and an apparatus for measuring a biological characteristic value such as a blood glucose level using near infrared spectroscopy.
生体特性値の測定は、一般に採血を伴うものであり、例えば、人の血糖値を測定する方法としては、採血した血液を用いて血糖に対するグルコース酸化酵素の反応を電気化学的に定量し、血糖値に換算するグルコースセンサー法が確立している。 The measurement of the biological characteristic value generally involves blood collection. For example, as a method for measuring the blood glucose level of a person, the reaction of glucose oxidase to blood glucose is electrochemically quantified using the collected blood, A glucose sensor method for converting to a value has been established.
これに対して、採血に伴う苦痛や採血針による感染等の問題を解決するために、非侵襲的に生体特性値を測定する方法が提案されており、その一つに近赤外分光法を用いた測定方法が知られている。これは、近赤外領域の波長の光を生体（人体）の特定箇所に照射し、生体からの拡散反射光又は透過光を分光器にて測定し、その拡散反射光又は透過光の吸光度（スペクトル）から血糖値などの生体特性値を算出しようとするものである。 On the other hand, in order to solve problems such as pain associated with blood collection and infection caused by a blood collection needle, a method for measuring biological property values non-invasively has been proposed. The measurement method used is known. This irradiates light of a wavelength in the near infrared region to a specific part of a living body (human body), measures diffuse reflection light or transmitted light from the living body with a spectroscope, and absorbs the diffuse reflected light or transmitted light ( The biological characteristic value such as blood glucose level is calculated from the spectrum.
血糖値の測定では、特定波長９２０ｎｍ付近と特定波長９８２ｎｍ付近を含む近赤外領域の波長の光を指などに照射して、その吸光度を求め、その値から血糖値を測定する方法が知られている。また、下記特許文献１に記載のものでは、複数の異なる波長からなる光を人体に照射して得られる人体からの透過光量から人体の血糖値を非侵襲的に測定することが提案されている。
In the measurement of blood glucose level, a method is known in which a finger or the like is irradiated with light having a wavelength in the near infrared region including a specific wavelength near 920 nm and a specific wavelength near 982 nm, the absorbance is obtained, and the blood glucose level is measured from that value. ing. Moreover, in the thing of the following
生体特性値の測定では、被測定対象である生体の状態に対応して、生体特性値が時間経過によってどのように変化するかを測定することが重要になっている。例えば、血糖値の測定であれば、食後の血糖値の時間経過による変化が分かれば、食後の血糖値上昇を抑えることができる食材を見つけて、肥満の防止や糖尿病の予防など、健康管理に役立てることが可能になる。 In the measurement of a biometric characteristic value, it is important to measure how the biometric characteristic value changes with the passage of time in accordance with the state of the living body to be measured. For example, in the case of blood glucose level measurement, if changes in blood glucose level after meals are known over time, food ingredients that can suppress the increase in blood glucose level after meals will be found and used for health management such as prevention of obesity and diabetes. It becomes possible to make use.
生体特性値の時間経過による変化を測定する場合、採血した血液を用いて測定しようすると、一定時間毎（例えば、数十分毎）に採血を行わなければならないので、測定対象者に多大な負担を掛けてしまう問題が生じる。前述した従来技術のように、非侵襲的な測定方法が確立すれば、この問題は解決するが、近赤外分光法によって生体特性値の時間経過による変化を求めようとすると、生体特性値に関連する吸光度を得る特定波長の選択が困難になり、正確な値を求めることができない問題が生じる。 When measuring changes in biological characteristic values over time, blood samples must be collected at regular time intervals (for example, every few tens of minutes) when measured using collected blood. The problem of multiplying. If a non-invasive measurement method is established as in the prior art described above, this problem can be solved. However, if a change in the biological characteristic value over time is obtained by near infrared spectroscopy, the biological characteristic value is It becomes difficult to select a specific wavelength to obtain the related absorbance, and there is a problem that an accurate value cannot be obtained.
血糖値などの生体特性値を近赤外分光法によって求める場合に、被測定対象の個体毎に、或いは同じ個体であっても測定する状態やその日間差によって、生体特性値に関連する吸光度を得る特定波長が異なる波長になることが分かってきた。このため、従来技術のように、特定波長を固定値として吸光度を求め、その吸光度と生体特性値との相関を求めようとしても、個体差や日間差、測定部位の体温変化や発汗状態などの状態差、測定部位における生体組織内での光路変化などによって、正確な値を得ることができず、実測値との間に大きな差が出てしまう問題があった。 When obtaining biological property values such as blood glucose levels by near infrared spectroscopy, the absorbance associated with the biological property values is determined for each individual subject to be measured, or even for the same individual, depending on the state to be measured and its daily difference. It has been found that the specific wavelength obtained is a different wavelength. For this reason, as in the prior art, even if the absorbance is obtained with a specific wavelength as a fixed value and the correlation between the absorbance and the biological property value is obtained, individual differences, daily differences, changes in body temperature of the measurement site, sweating conditions, etc. There is a problem in that an accurate value cannot be obtained due to a state difference, an optical path change in a living tissue at a measurement site, and a large difference appears between the measured value and the measured value.
本発明は、このような問題に対処することを課題の一例とするものである。すなわち、近赤外分光法を用いた新たな生体特性値の測定方法を提案し、精度の高い生体特性値の測定を可能にすること、生体特性値の時間経過による変化を測定対象者への負担を減らしながら精度良く測定することができること、などが本発明の目的である。 This invention makes it an example of a subject to cope with such a problem. In other words, we propose a new method for measuring biological characteristic values using near-infrared spectroscopy, enabling highly accurate measurement of biological characteristic values, and measuring changes in biological characteristic values over time to the measurement subject. It is an object of the present invention to be able to measure with high accuracy while reducing the burden.
このような目的を達成するために、本発明による近赤外分光法を用いた生体特性値測定方法及び測定装置は、以下の構成を具備するものである。 In order to achieve such an object, a biological property value measuring method and measuring apparatus using near-infrared spectroscopy according to the present invention have the following configurations.
生体特性値の時間経過に伴う変化を測定するに際して、複数の経過時間において、生体特性値の実測値を得ると共に、生体に近赤外光を照射し、生体からの拡散反射光又は透過光を受光して、近赤外の設定波長範囲で複数の波長毎の吸光度を求め、前記実測値に対して吸光度の相関が高い波長を特定し、特定した波長の吸光度から前記実測値を算出する計算式を導出し、他の経過時間において、生体に近赤外光を照射し、生体からの拡散反射光又は透過光を受光して、特定した波長の吸光度を求めて、前記計算式から生体特性値を算出することを特徴とする近赤外分光法を用いた生体特性値測定方法。 When measuring changes in the biological characteristic value over time, the measured value of the biological characteristic value is obtained at a plurality of elapsed times, the near-infrared light is irradiated to the living body, and diffused reflected light or transmitted light from the living body is emitted. Calculation to receive light, determine absorbance for each of a plurality of wavelengths in the near-infrared set wavelength range, identify a wavelength having a high correlation of absorbance to the measured value, and calculate the measured value from the absorbance at the specified wavelength Deriving the equation, irradiating the living body with near-infrared light at another elapsed time, receiving diffuse reflection light or transmitted light from the living body, obtaining the absorbance at the specified wavelength, A bio-characteristic value measurement method using near-infrared spectroscopy, characterized by calculating a value.
生体特性値の時間経過に伴う変化を測定する近赤外分光法を用いた生体特性値測定装置において、入力された生体特性値の実測値と近赤外分光装置が求めた吸光度とを演算処理する演算処理部を備え、前記演算処理部は、生体特性値の時間経過に伴う変化を測定するに際して、複数の経過時間において、実測された生体特性値の実測値と、近赤外の設定波長範囲で複数の波長毎に求めた吸光度とから、前記実測値に対して吸光度の相関が高い波長を特定し、特定した波長の吸光度から前記実測値を算出する計算式を導出し、他の経過時間において、特定した波長の吸光度と前記計算式から生体特性値を算出することを特徴とする近赤外分光法を用いた生体特性値測定装置。 In a biological property value measurement device using near infrared spectroscopy that measures changes in biological property values over time, the measured value of the input biological property value and the absorbance obtained by the near infrared spectroscopy device are processed. An arithmetic processing unit that performs measurement of a change in the biometric characteristic value with time, and the measured value of the biometric characteristic value measured at a plurality of elapsed times and a near-infrared set wavelength. From the absorbance obtained for each of a plurality of wavelengths in the range, identify a wavelength having a high correlation of absorbance with respect to the actual measurement value, derive a calculation formula for calculating the actual measurement value from the absorbance of the identified wavelength, A biological property value measuring apparatus using near-infrared spectroscopy, characterized in that a biological property value is calculated from absorbance at a specified wavelength and the calculation formula over time.
このような特徴を有する本発明は、生体特性値の時間経過に伴う変化を測定するに際して、一連の測定毎に最適な波長を特定して吸光度を求め、その吸光度との相関で生体特性値を求めることができるので、近赤外分光法によって精度の高い生体特性値の測定を行うことができる。また、生体特性値の時間経過に伴う変化を、一部実測値を得ること無く測定することができるので、採血などに伴う測定対象者の負担を減らしながら、精度良く測定することができる。 In the present invention having such characteristics, when measuring changes in the biological characteristic value over time, the optimal wavelength is specified for each series of measurements to determine the absorbance, and the biological characteristic value is determined by correlation with the absorbance. Since it can obtain | require, the measurement of a biological characteristic value with high precision can be performed by near-infrared spectroscopy. In addition, since changes in the biological characteristic value over time can be measured without obtaining some actual measurement values, it is possible to measure with high accuracy while reducing the burden on the measurement subject accompanying blood collection.
また、本発明によると、個体差や日間差、測定部位の体温変化や発汗状態などの状態差、測定部位における生体組織内での光路変化などがあっても、測定毎に最適な波長を特定して、生体特性値との相関が高い吸光度を求めて、それによって生体特性値を算出することができるので、いつでも、どこでも、誰に対してでも適用可能な、安定した測定精度を担保できる生体特性値測定方法及び装置を提供することができる。 In addition, according to the present invention, even when there are individual differences, daily differences, changes in body temperature of the measurement site, state differences such as sweating, and optical path changes in the living tissue at the measurement site, the optimum wavelength is specified for each measurement. Since it is possible to calculate an absorbance having a high correlation with the biological property value and thereby calculate the biological property value, it is possible to ensure stable measurement accuracy that can be applied to anyone at any time, anywhere. A characteristic value measuring method and apparatus can be provided.
以下、図面を参照して本発明の実施形態を説明する。図１は、本発明の実施形態に係る生体特性値測定装置の構成例を示した説明図である。生体特性値測定装置１は、近赤外分光装置１０と演算処理部２０を備えている。近赤外分光装置１０は、周知の構成であり、測光部１１と分光部１２と光源部１３とを備えている。測光部１１は、光源部１３から出射される近赤外光を被測定対象（生体）Ｍに照射する光照射部１４と、被測定対象（生体）Ｍからの拡散反射光又は透過光を受光する受光部１５を備えている。分光部１２は、受光部１５で受光した光から特定波長の吸光度を求めて出力する。演算処理部２０は、生体特性値の実測値が入力されると共に、分光部１２から出力される吸光度の測定値が入力され、それらを演算処理することによって、実測されていない経過時間の生体特性値を計算出力する。
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a configuration example of a biological characteristic value measuring apparatus according to an embodiment of the present invention. The biological characteristic
演算処理部２０の処理工程によって、本発明の実施形態に係る近赤外分光法を用いた生体特性値測定方法が実行される。以下に、演算処理部２０の処理工程を説明する。
The biological characteristic value measurement method using near infrared spectroscopy according to the embodiment of the present invention is executed by the processing steps of the
図２は、演算処理部２０によって求められる生体特性値の測定結果を示している。ここでは、生体特性値の時間経過に伴う変化を求めており、測定開始からの経過時間ｔ０〜ｔ６においてどのように生体特性値が変化するかを、一部を実測値で求め、その他を計算値で求めている。ここでの実測値とは、採血による血液から測定される値などを指している。
FIG. 2 shows the measurement result of the biological characteristic value obtained by the
具体的には、経過時間ｔ０における生体特性値の実測値Ａ０、経過時間ｔ１における生体特性値の実測値Ａ１、経過時間ｔ２における生体特性値の実測値Ａ２、経過時間ｔ３における生体特性値の実測値Ａ３、経過時間ｔ６における生体特性値の実測値Ａ６をそれぞれ求め、各経過時間ｔ０〜ｔ６において近赤外分光装置が求めた吸光度と前述した実測値とから、経過時間ｔ４における生体特性値（計算値）Ａ４*、経過時間ｔ５における生体特性値（計算値）Ａ５*を算出する。 Specifically, the measured value A0 of the biological characteristic value at the elapsed time t0, the measured value A1 of the biological characteristic value at the elapsed time t1, the measured value A2 of the biological characteristic value at the elapsed time t2, and the measured biological characteristic value at the elapsed time t3. A measured value A6 of the biological characteristic value at the time A6 and the elapsed time t6 is obtained, and the biological characteristic value at the elapsed time t4 (from the absorbance obtained by the near-infrared spectrometer at each elapsed time t0 to t6 and the above-described actual measured value ( Calculated value) A4 * and biological characteristic value (calculated value) A5 * at elapsed time t5 are calculated.
演算処理部２０には、図３に示すように、実測値Ａ０，Ａ１，Ａ２，Ａ３，Ａ６と、吸光度Ｉλi tが入力される。吸光度Ｉλi tは、経過時間ｔ（＝ｔ１，ｔ２，…，ｔ６）における波長λｉ（＝λ１，λ２，…，λn-1，λｎ）の吸光度である。波長λｉは、近赤外の設定波長範囲によって決められた複数の波長であり、例えば、７００〜１０５０ｎｍの範囲で、数〜数十ｎｍ毎に設定される波長であって、λ１＝７００ｎｍ，λ２＝７０１ｎｍ，λ３＝７０２ｎｍ，…，λn-1＝１０４９ｎｍ，λｎ＝１０５０ｎｍのように１ｎｍ毎に設定することができる。
The
演算処理部２０は、波長λｉ毎に、（吸光度，実測値）の相関係数を求める。すなわち、波長λｉ毎に、（Ｉλi t0，Ａ０），（Ｉλi t1，Ａ１），（Ｉλi t2，Ａ２），（Ｉλi t3，Ａ３），（Ｉλi t6，Ａ６）の相関係数を求める。そして、相関係数が高い波長λｉを一つ又は複数特定する。ここで相関係数が高いとは、相関係数の絶対値が０．７以上、或いは、最も高い相関係数の絶対値（最大値）−０．１以上に設定することができる。
The
相関係数が高い波長をλｔとすると、波長λｔの吸光度Ｉλt tから実測値を算出する計算式を導出する。複数の波長λｔを特定した場合には、特定された各波長の吸光度にその波長の相関関係を乗じて足し合わせた値（重み付き和）を説明変数（Ｘ）、生体特性値を目的変数（Ｙ）として、Ｙ＝ａ・Ｘ＋ｂが成り立つ係数ａと切片ｂの値を推定する単回帰を行い、このＹ＝ａ・Ｘ＋ｂによって吸光度を生体特性値に変換する計算式にする。 If a wavelength having a high correlation coefficient is λt, a calculation formula for calculating an actual measurement value is derived from the absorbance I λt t of the wavelength λt. When a plurality of wavelengths λt are specified, a value (weighted sum) obtained by multiplying the absorbance of each specified wavelength by the correlation of the wavelengths is added as an explanatory variable (X), and a biological characteristic value is set as an objective variable ( As Y), a simple regression is performed to estimate the values of the coefficient a and the intercept b that satisfy Y = a · X + b, and a calculation formula for converting the absorbance into a biological characteristic value by Y = a · X + b.
そして、Ｉλt t4，Ｉλt t5を説明変数Ｘに代入して、Ｙ＝ａ・Ｘ＋ｂから、経過時間ｔ４，ｔ５における生体特性値Ａ４*，Ａ５*を算出する。このような生体特性値の測定方法によると、生体特性値の経過時間に伴う変化を測定するに際して、採血などを伴う実測値の取得を経過時間の一部に止めることができ、その他の経過時間での測定を、採血などを伴わない計算値で補うことができるので、測定対象者への負担を減らしながら、精度の高い測定を実現することができる。 Then, by substituting I λt t4 and I λt t5 into the explanatory variable X, biological characteristic values A4 * and A5 * at elapsed times t4 and t5 are calculated from Y = a · X + b. According to such a method for measuring a biological characteristic value, when measuring a change with the elapsed time of the biological characteristic value, acquisition of an actual measurement value with blood sampling or the like can be stopped as a part of the elapsed time, and other elapsed time Since the measurement in can be supplemented with a calculated value that does not involve blood collection or the like, highly accurate measurement can be realized while reducing the burden on the measurement subject.
なお、前述した説明では、吸光度から生体特性値を求める例を示しているが、それに換えて、吸光度の変化量から生体特性値の変化量を求めるようにしてもよい。吸光度から生体特性値を求める場合や吸光度の変化量から生体特性値を求める場合には、１回の測定で得られた波長毎の吸光度に対して、光拡散状態の違いによる吸光度の加算的・乗算的変動を除去するために、予めSavitzky-Golay法による２次微分処理を施すことが好ましい。また、２次微分処理の他に、SC（Multiplicative Scatter Correction）やSNV（Standard Normal Variate）といった方法を採用することもできる。 In the above description, the example in which the biological characteristic value is obtained from the absorbance is shown, but instead, the amount of change in the biological characteristic value may be obtained from the amount of change in absorbance. When obtaining a biological characteristic value from the absorbance or obtaining a biological characteristic value from the amount of change in absorbance, the absorbance due to the difference in the light diffusion state is added to the absorbance for each wavelength obtained in one measurement. In order to remove the multiplicative fluctuation, it is preferable to perform a second-order differentiation process by the Savitzky-Golay method in advance. In addition to the secondary differentiation process, methods such as SC (Multiplicative Scatter Correction) and SNV (Standard Normal Variate) can also be employed.
以下、生体特性値の例として人の血糖値を取り上げ、食後の時間経過に伴う血糖値変化から、食品のＧＩ測定を行う例を説明する。 Hereinafter, an example in which a person's blood glucose level is taken as an example of a biometric characteristic value and GI measurement of a food is performed from a blood glucose level change with time after meal will be described.
ＧＩ（グリセミックス・インデックス）は、食後血糖値の上昇度を示す指標であり、食品毎にＧＩを求めて低ＧＩ食品を特定することで、肥満や糖尿病の予防・改善の観点から食生活を見直す上で有効な指標とされている。ＧＩは、ＧＩ＝（検査食のＩＡＵＣ／基準食のＩＡＵＣ）×１００で定義されており、多数の被験者による経口糖質負荷試験で求められる。ここで、ＩＡＵＣは、食後２時間までの血糖値上昇曲線下面積を指しており、食後から２時間までの時間経過に伴う血糖値変化（血糖値変化量）を求めることが、ＧＩ測定には不可欠になっている。 GI (Glycemic Index) is an index that indicates the degree of increase in postprandial blood glucose levels. By finding GI for each food and identifying low GI foods, the dietary life can be improved from the viewpoint of prevention and improvement of obesity and diabetes. It is an effective index for review. The GI is defined as GI = (IAUC of the test meal / IAUC of the reference meal) × 100, and is obtained by an oral carbohydrate tolerance test by a large number of subjects. Here, IAUC refers to the area under the blood sugar level increase curve until 2 hours after meal, and it is necessary to obtain the blood sugar level change (blood sugar level change amount) with the passage of time from 2 hours after meal to GI measurement. It has become essential.
検査食又は基準食のＩＡＵＣを一つ求めるためには、１人の被験者で食前（空腹時）からの血糖値変化量ΔＢＧｔを、経過時間ｔ＝０（空腹時），１５，３０，４５，６０，９０，１２０ｍｉｎの７回測定することが必要になる。そのために、前述した生体特性値測定装置１を用いた測定を行い、被験者が検査食又は基準食を食べてから経過時間ｔ＝０（空腹時），１５，３０，４５，６０，９０，１２０ｍｉｎにおいて、波長λ毎に空腹時からの吸光度変化量（２次微分値）ΔＩλを求める。但し、λ＝７００，７０１，…８５１，８５２，…，１０５０ｎｍとする。また同時に、経過時間６０ｍｉｎと９０ｍｉｎを除いて、被験者に対して採血を行い、経過時間ｔ＝０（空腹時），１５，３０，４５，１２０ｍｉｎにおける血糖値実測値を測定する。血糖値実測値は、経過時間毎に採血した血液に対してグルコースセンサー法で測定する。
In order to obtain one IAUC for the test meal or the reference meal, the change in blood glucose level ΔBGt from before eating (fasting) in one subject is expressed as elapsed time t = 0 (fasting), 15, 30, 45, It is necessary to measure seven times at 60, 90, and 120 min. Therefore, the measurement using the above-described biological property
これによって、演算処理部２０には、経過時間ｔ＝０，１５，３０，４５，１２０ｍｉｎ毎に測定された実測値の血糖値変化量ΔＢＧｔと経過時間ｔ＝０，１５，３０，４５，６０，９０，１２０ｍｉｎ毎に測定された吸光度変化量ΔＩλが入力される。演算処理部２０は、この入力データに基づいて、血糖値変化量ΔＢＧｔと吸光度変化量ΔＩλの相関係数ｒを波長λ毎に求めて、相関の高い波長λ*を特定する。ここでは、吸光度変化量として２次微分値を適用しているので、血糖値変化量ΔＢＧｔと吸光度変化量ΔＩλの相関係数ｒは負の値になる。相関の高い波長λ*としては、相関係数ｒの負の最大値＋０．１以下に対応する波長λ*を単数又は複数特定する。
As a result, the
演算処理部２０は、特定した波長λ*における吸光度変化量ΔＩλ* t（ｔ＝０，１５，３０，４５，１２０ｍｉｎ）と実測値の血糖値変化量ΔＢＧｔ（ｔ＝０，１５，３０，４５，１２０ｍｉｎ）から、血糖値変化量ΔＢＧｔを目的変数（Ｙ）とし、吸光度変化量ΔＩλ*を説明変数（Ｘ）とする計算式を導出する。具体的には、目的変数（Ｙ）と説明変数（Ｘ）の単回帰分析を行い、Ｙ＝ａ＋ｂ・Ｘのａ及びｂを求める。ここで、波長λ*を複数特定した場合には、説明変数（Ｘ）を吸光度変化量ΔＩλ*の重み付き和（Σｒ*・ΔＩλ*、ｒ*はλ*毎の相関係数）とする。
The
この計算式（Ｙ＝ａ＋ｂ・Ｘ）を用いて、Ｘ＝ΔＩλ*（ｔ＝６０ｍｉｎ）を代入して、Ｙ＝ΔＢＧｔ（ｔ＝６０ｍｉｎ）を求め、Ｘ＝ΔＩλ*（ｔ＝９０ｍｉｎ）を代入して、Ｙ＝ΔＢＧｔ（ｔ＝９０ｍｉｎ）を求める。これによって、一部は実測値であって、一部は計算値である血糖値変化量ΔＢＧｔを、経過時間ｔ＝０（空腹時），１５，３０，４５，６０，９０，１２０ｍｉｎの７回測定することができ、この測定結果から検査食又は基準食のＩＡＵＣを求めることができる。 Using this calculation formula (Y = a + b · X), X = ΔI λ * (t = 60 min) is substituted to obtain Y = ΔBGt (t = 60 min), and X = ΔI λ * (t = 90 min) Is substituted for Y = ΔBGt (t = 90 min). As a result, the blood glucose level change amount ΔBGt, which is partly measured values and partly calculated values, is measured seven times at elapsed time t = 0 (fasting), 15, 30, 45, 60, 90, 120 min. IAUC of the test meal or the reference meal can be obtained from the measurement result.
以上説明したように、本発明の実施形態に係る測定方法及び測定装置によると、生体特性値の時間経過に伴う変化を測定するに際して、一連の測定毎に最適な波長を特定して吸光度を求め、その吸光度との相関で生体特性値を求めることができるので、近赤外分光法によって精度の高い生体特性値の測定を行うことができる。また、生体特性値の時間経過に伴う変化を、一部実測値を得ること無く測定することができるので、採血などに伴う測定対象者の負担を減らしながら、精度良く生体特性値を測定することができる。 As described above, according to the measurement method and the measurement apparatus according to the embodiment of the present invention, when measuring the change of the biological characteristic value with time, the optimal wavelength is specified for each series of measurements to obtain the absorbance. Since the biological characteristic value can be obtained by correlation with the absorbance, the biological characteristic value can be measured with high accuracy by near infrared spectroscopy. In addition, since changes in biometric values over time can be measured without obtaining some actual measured values, it is possible to measure biometric values with high accuracy while reducing the burden on the measurement subject due to blood collection. Can do.
特に、食品分野での糖尿病や肥満の予防・改善、医療分野での糖尿病患者の血糖値管理などで注目されているＧＩ（グリセミックス・インデックス）の測定では、食品のＧＩを求めるために、検査食や基準食を被験者が実際に摂取して、摂取後の血糖値変化を測定する経口糖質負荷試験を行う必要があり、その際、従来は一つのＩＡＵＣ（食後２時間までの血糖値上昇曲線下面積）を得るために２時間のうちに７回の採血が必要であったが、本発明の測定方法を用いると、この採血の回数を一部省いて、実測値を計算値に置き換え、しかも精度の高いＩＡＵＣを求めることができる。これにより、ＧＩ測定において被験者の負担を軽減することが可能になる。 In particular, in the measurement of GI (Glycemic Index), which is attracting attention for the prevention and improvement of diabetes and obesity in the food field, and the management of blood sugar levels in diabetic patients in the medical field, a test is performed to determine the GI of food. It is necessary to conduct an oral carbohydrate tolerance test in which a subject actually ingests a meal or a reference meal and measures changes in blood glucose level after the intake. In this case, conventionally, one IAUC (increased blood glucose level up to 2 hours after meal) In order to obtain the area under the curve, seven blood collections were required within 2 hours. However, when the measurement method of the present invention was used, some of the blood collections were omitted and the actual measurement values were replaced with calculated values. In addition, a highly accurate IAUC can be obtained. This makes it possible to reduce the burden on the subject in the GI measurement.
１：生体特性値測定装置，１０：近赤外分光装置，１１：測光部，
１２：分光部，１３：光源部，１４：光照射部，１５：受光部，
２０：演算処理部，Ｍ：被測定対象
1: biological characteristic value measuring device, 10: near-infrared spectroscopic device, 11: photometry unit,
12: Spectroscopic unit, 13: Light source unit, 14: Light irradiation unit, 15: Light receiving unit,
20: arithmetic processing unit, M: measurement target
Claims (5)
複数の経過時間において、生体特性値の実測値を得ると共に、生体に近赤外光を照射し、生体からの拡散反射光又は透過光を受光して、近赤外の設定波長範囲で複数の波長毎の吸光度を求め、前記実測値に対して吸光度の相関が高い波長を特定し、特定した波長の吸光度から前記実測値を算出する計算式を導出し、
他の経過時間において、生体に近赤外光を照射し、生体からの拡散反射光又は透過光を受光して、特定した波長の吸光度を求めて、前記計算式から生体特性値を算出することを特徴とする近赤外分光法を用いた生体特性値測定方法。 When measuring changes in biological characteristic values over time,
In a plurality of elapsed times, the measured value of the biological characteristic value is obtained, the living body is irradiated with near infrared light, diffuse reflected light or transmitted light from the living body is received, and a plurality of wavelengths in the near infrared set wavelength range are received. Obtain the absorbance for each wavelength, identify the wavelength having a high correlation of absorbance with respect to the measured value, and derive a calculation formula for calculating the measured value from the absorbance of the identified wavelength,
At other elapsed times, irradiate the living body with near-infrared light, receive diffusely reflected light or transmitted light from the living body, determine the absorbance at the specified wavelength, and calculate the biological characteristic value from the above formula A method for measuring biological property values using near infrared spectroscopy.
入力された生体特性値の実測値と近赤外分光装置が求めた吸光度とを演算処理する演算処理部を備え、
前記演算処理部は、
生体特性値の時間経過に伴う変化を測定するに際して、
複数の経過時間において、実測された生体特性値の実測値と、近赤外の設定波長範囲で複数の波長毎に求めた吸光度とから、前記実測値に対して吸光度の相関が高い波長を特定し、特定した波長の吸光度から前記実測値を算出する計算式を導出し、
他の経過時間において、特定した波長の吸光度と前記計算式から生体特性値を算出することを特徴とする近赤外分光法を用いた生体特性値測定装置。 In a biological property value measurement apparatus using near infrared spectroscopy that measures changes with time of biological property values,
An arithmetic processing unit that performs arithmetic processing on the measured value of the input biological characteristic value and the absorbance obtained by the near-infrared spectrometer,
The arithmetic processing unit includes:
When measuring changes in biological characteristic values over time,
Identify wavelengths that have a high correlation of absorbance with the measured values from the measured values of the measured biological characteristic values at multiple elapsed times and the absorbance values obtained for each of the multiple wavelengths in the near-infrared wavelength range. And deriving a calculation formula for calculating the actual measurement value from the absorbance at the specified wavelength,
A biological property value measuring apparatus using near-infrared spectroscopy, wherein the biological property value is calculated from the absorbance at the specified wavelength and the calculation formula at another elapsed time.
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