JP2000258343A - Method and apparatus for measurement of blood sugar level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax a measuring condition when a blood sugar level is found by using the quadratic differential value of an absorbance and to enhance the measuring accuracy of the measurement of a noninvasive blood sugar level. SOLUTION: In a state that the flow of venous blood in a part F to be measured is stopped while a pressure force is made to act by a cuff 8, the part F, to be measured, in a living body is irradiated with near-infrared rays at near-field wavelengths λ1, λ2, λ3 from a light source 2. Intensities of transmitted rays at the three wavelengths λ1, λ2, λ3 are detected simultaneously by a photodetector 4. The temperature of the part F to be measured is measured by a temperature measuring device 9. In a computing and processing circuit 14, the quadratic differential value of the absorbance of the near-infrared rays n the part F to be measured is calculated on the basis of transmitted-light-intensity detection values which are obtained simultaneously regarding the three wavelengths. Its means value within a prescribed time is found, and it is corrected so as to correspond to a deviation from the reference temperature of a temperature detection value in the part F to be measured. A temperature-corrected mean value is found. A blood sugar level, in the living body, which corresponds to it is found.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for non-invasively measuring a blood glucose level in a living body.

[0002]

2. Description of the Related Art Diabetics frequently (e.g., daily) receive an indication of insulin administration for controlling blood sugar levels (generally, blood glucose levels). It is required to measure the blood glucose level several times. Sampling blood at each such frequent measurement is a great pain for the patient.
Therefore, it is desired to measure the blood glucose level without actually collecting blood from the patient, that is, non-invasively, and as a method for this, infrared light is applied to a part of the patient, for example, a site to be measured such as an earlobe or a finger. It has been proposed to detect the infrared light transmitted through the measurement site and to measure the degree of infrared absorption by the measurement site. In this method, by appropriately selecting the wavelength of the infrared light to be used, an absorbance value that reflects the infrared absorption by glucose in the measurement site to a considerable extent is obtained, and a blood glucose value is obtained based on the absorbance value.

However, in such optical non-invasive blood glucose measurement, the condition of the measurement site (such as the optical path length of infrared light passing through the measurement site) is not constant but changes due to pulsation and the like. Therefore, it is inevitable that the measurement is accompanied by a certain error based on such factors. There is a strong demand for minimizing this measurement error.

[0004] One method for reducing the measurement error is as follows.
It has been pointed out that the measurement may be performed not by measuring the blood sugar level from the absorbance itself but by using a second derivative of the absorbance (see Japanese Patent Application Laid-Open No. 5-176917). In this method, the absorbance is measured at three wavelengths that are different and close to each other, and a variation (second absorbance value) corresponding to a second derivative calculated from these measured absorbance values by addition and subtraction.
Is used for blood glucose measurement.

[0005] However, when measuring the blood sugar level based on the second derivative of the absorbance, the measured blood sugar level tends to be different when environmental conditions and other measurement conditions are different. From the viewpoint, it is necessary to keep environmental conditions and other measurement conditions as constant as possible, which complicates blood glucose measurement based on the second derivative of absorbance.

Accordingly, an object of the present invention is to relax the measurement conditions when obtaining a blood glucose level using the second derivative of the absorbance,
It is to improve the measurement accuracy of noninvasive blood glucose measurement.

[0007]

According to the present invention, in order to achieve the above-mentioned object, near-infrared light having three different wavelengths and being close to each other is irradiated to a site to be measured of a living body. In the blood sugar level measuring method for detecting the intensity of the transmitted light of the three wavelengths transmitted through the measurement site and obtaining the blood glucose level in the living body based on the detected transmitted light intensity values for the three wavelengths, the transmission of the three wavelengths is performed. The temperature of the living body is detected together with the detection of the light intensity, and the second derivative of the absorbance of the near-infrared light by the measured portion is calculated from the transmitted light intensity detection values for the three wavelengths, within a predetermined time. The representative value of the second derivative of the absorbance is obtained, and the representative value is corrected according to the deviation of the detected biological temperature from the reference temperature to obtain a temperature-corrected representative value. The corresponding organism And obtaining a blood glucose level of the blood glucose measuring method, it is provided.

In one embodiment of the present invention, the living body temperature detection obtains a second derivative of the absorbance at the measurement site using near infrared light having three wavelengths different from the three wavelengths. It is performed by converting the second derivative of the absorbance using a calibration curve.

In one embodiment of the present invention, the intensity of the transmitted light of the three wavelengths is simultaneously detected, and the second derivative of the absorbance is calculated based on the simultaneously detected transmitted light intensity.

In one embodiment of the present invention, the absorbance 2
As a representative value of the second derivative, a value obtained by dividing the value obtained by integrating the second derivative of the absorbance for a predetermined time by the predetermined time is used, or the maximum value of the second derivative of the absorbance within a predetermined time is used. The average of the value and the minimum value is used.

In one aspect of the present invention, the intensity of the transmitted light of the three wavelengths is detected in a state where the venous blood flow at the measurement site is stopped by applying a pressing force to the living body.

In one embodiment of the present invention, at least one of the three wavelengths of transmitted light transmitted through the measurement site.
The intensity of the near-infrared light of the three wavelengths incident on the measurement site is controlled such that the integrated value of the three intensities over a certain period of time or the time average thereof is close to a predetermined value.

Further, according to the present invention, in order to achieve the above-mentioned object, near-infrared light having three different wavelengths and being close to each other is radiated to a measurement site of a living body and transmitted through the measurement site. In the blood glucose level measuring device that detects the intensity of the transmitted light of the three wavelengths and obtains the blood glucose level in the living body based on the transmitted light intensity detection values of the three wavelengths, the near infrared light of the three wavelengths is A light source that emits light, a photodetector that detects the transmitted light of the three wavelengths emitted from the light source and transmitted through the living body, a thermometer that detects the temperature of the living body, and the light detector that is obtained from the light detector A second derivative of the absorbance of the near-infrared light by the measurement site is calculated by performing an operation based on the detected values of the transmitted light intensities for the three wavelengths, and a representative value of the second derivative of the absorbance within a predetermined time is calculated. Seeking, before Arithmetic processing means for correcting the representative value in accordance with the deviation of the detected biological temperature from the reference temperature to obtain a temperature-corrected representative value, and obtaining a blood glucose level in the living body corresponding to the temperature-corrected representative value; A blood glucose level measuring device is provided, comprising:

In one embodiment of the present invention, the temperature measuring means uses the arithmetic processing means, and uses the near-infrared light of three different wavelengths from the three wavelengths to measure the measured portion. To obtain the second derivative of the absorbance,
The temperature of the measurement site is measured by converting the next differential value using a calibration curve.

In one embodiment of the present invention, the arithmetic processing means corrects the representative value using a temperature correction coefficient in accordance with a deviation of the detected biological temperature from the reference temperature.

In one embodiment of the present invention, the arithmetic processing means is obtained by dividing a value obtained by integrating the second derivative of the absorbance for a predetermined time as a representative value of the second derivative of the absorbance by the predetermined time. Value, or
The average value of the maximum value and the minimum value of the second derivative of the absorbance within a predetermined time is used.

In one embodiment of the present invention, at least one of the transmitted lights of the three wavelengths transmitted through the measurement site.
Means for controlling the intensity of the near-infrared light of the three wavelengths incident on the measurement site so that the integrated value of the three intensities for a predetermined time or the time average thereof is close to the predetermined value.

In one embodiment of the present invention, there is provided means for applying a pressing force to the living body.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an embodiment of a blood sugar level measuring apparatus according to the present invention in which a blood sugar level measuring method according to the present invention is carried out.

In FIG. 1, reference numeral 2 denotes a light source. The light sources have three different wavelengths λ1, λ2, λ3 which are close to each other.
It emits near-infrared light of (λ1 <λ2 <λ3). Wavelength λ1,
As λ2 and λ3, for example, 902 nm, 912 nm
And 922 nm.

FIG. 2 shows a specific example of the light source 2. FIG.
1A includes a broad light lamp 21 that emits light including near-infrared light having wavelengths λ1, λ2, and λ3. Part of the light emitted from the lamp 21 is emitted forward (to the right in FIG. 2) through the stop 22 as light for irradiating the measured portion. Another part of the light emitted from the lamp 21 enters the rear (left side in FIG. 2) lamp light amount monitor 23. Instead of the monitor 23, a combination of a half mirror 24 disposed in front of the stop 22 and a monitor 25 for detecting light reflected by the half mirror can be used. Monitors 23 and 25 output light quantity monitor electric signals. 2B includes semiconductor lasers 26-1, 26-2, and 26-3 that emit near-infrared light having wavelengths λ1, λ2, and λ3. Light for irradiating the measurement site is emitted forward (to the right in FIG. 2) from these lasers. The light emitted from the semiconductor lasers 26-1, 26-2, and 26-3 to the rear (to the left in FIG. 2) is a light amount monitor 27.
-1, 27-2 and 27-3. These monitors output light quantity monitor electrical signals. Light emitted forward from the lasers 26-1 and 26-3 is reflected by the mirrors 28-1 and 28-2 and the half mirror 29-29, respectively.
The light emitted from the laser 26-2 is combined with the light emitted forward by the laser beams 1 and 29-2, and emitted forward as one light beam including near-infrared light having wavelengths λ1, λ2 and λ3.

In FIG. 1, reference numeral 4 denotes a photodetector, which is arranged at a position where it can receive the light emitted from the light source 2. Between the light detector 4 and the light source 2, there is a measurement site arrangement portion 6 for arranging a measurement site F of a living body, for example, a human body, for example, a finger, and is inserted into the measurement site arrangement portion 6. A cuff 8 for applying a desired pressing force to the measured portion F by applying air pressure is provided. In addition, the cuff 8 stops the venous blood flow (including sufficient suppression) while maintaining the arterial blood flow at the site F to be measured for an appropriate time by adjusting the air injection amount by an air pump. It is preferable to use one that can maintain the state. The cuff 8 has at least the wavelength λ1,
The passage of the near-infrared light of λ2 and λ3 is made of a material that can transmit the near-infrared light or has a structure that allows the transmission of the near-infrared light. As a cuff that can maintain a state in which venous blood flow is stopped while maintaining arterial blood flow in the measurement site F, besides the one that entirely surrounds the measurement site F, It is also possible to use a material wound around a part close to the heart (when the part F to be measured is the tip of a finger, the root part of the finger). A contact-type thermometer 9 that detects the surface temperature of the inserted measurement-target portion F is provided in the measurement-target-placement unit 6 (a radiation thermometer is used instead of the contact-type thermometer). Is also possible).

FIG. 3 shows a specific example of the photodetector 4. The light including the near-infrared light of wavelengths λ1, λ2, and λ3 emitted from the light source 2 and passing through the measurement site F arranged in the measurement site arrangement unit 6 is separated by the diffraction grating 31, and the light of the wavelength λ1 is The light having the wavelength λ2 which is incident on the light receiving section 32-1 is
2, and the light having the wavelength λ3 enters the light receiving unit 32-3. These light receiving units output light quantity detection electric signals.

When a light source that emits broad light as shown in FIG. 2A is used as the light source 2, the desired wavelengths λ1 and λ are provided in the optical path on the light source side or on the photodetector side.
It is possible to dispose a filter that passes only the light in the immediate vicinity of each of 2 and λ3.

The three light receiving sections 32-1 and 32-2 of the photodetector 4
The electrical outputs (proportional to the intensity of the received light) of −2 and 32-3 are respectively supplied from variable gain amplifiers 10-1, 10-2 and 10-3 as shown in FIG. The signal is amplified, A / D converted by the A / D converters 12-1, 12-2, and 12-3, and input to the arithmetic processing circuit 14. Also, the light amount monitors 23, 25, 27-1, 27 of the light source 2
Outputs of −2 and 27-3 are also input to the arithmetic processing circuit 14 after being A / D converted. Further, the output of the thermometer 9 is also A
After being / D converted, it is input to the arithmetic processing circuit 14.

In the arithmetic processing circuit 14, the blood sugar level is measured as follows.

Assuming that the intensity of light of wavelength λ incident on the site F to be measured is I ₀ (λ) and the intensity of light of wavelength λ transmitted through the site F to be measured is I (λ), Absorbance AB
S (λ) is obtained by ln (I ₀ (λ) / I (λ)). The incident light intensity I ₀ (λ) is measured by a light source light amount monitor 27−
It is obtained by multiplying the outputs of 1, 27-2, 27-3 by a predetermined coefficient (in the case of the light amount monitors 23, 25, it is obtained by multiplying the outputs by the predetermined coefficients for each of the wavelengths λ1, λ2, λ3). . This absorbance ABS (λ) periodically changes in accordance with the pulsation of the measurement site F. That is, the measured portion F
Includes a body tissue portion and arterial blood flow and venous blood flow flowing therethrough, the pulsation changes the transmitted light path length, and the component composition ratio in the transmitted light path also changes.
(Λ).

In the present embodiment, for each of the wavelengths λ1, λ2, and λ3, I ₀ (λ), I ₀ (λ) obtained in parallel by high-speed sampling, for example, about every 10 to 20 msec.
Based on (λ), absorbance ABS (λ1), ABS (λ
2), ABS (λ3) is calculated. This absorbance ABS
(Λ1), ABS (λ2), ABS (λ3)
Calculate the second derivative of the absorbance ABS ”(λ2). The second derivative of the absorbance ABS” (λ2) is calculated as: ABS ”(λ2) = [ABS (λ1) −ABS (λ2)] − [ABS (λ2) − ABS (λ3)] = [ABS (λ1) + ABS (λ3)] − 2ABS (λ), where λ2−λ1 = λ3−λ2 = Δ, and λ
If 2 = λ, ABS ”(λ) = [ABS (λ−Δ) + ABS (λ +
Δ)]-2 ABS (λ). As described above, Δ may be, for example, 10 nm or may be 5 nm.

The second derivative of the absorbance is determined by taking advantage of the fact that the light absorption by glucose fluctuates according to the wavelength of light, and selecting three wavelengths close to each other in a wavelength range where the fluctuation due to this wavelength appears as large as possible. It is defined as a value corresponding to the second derivative.

FIG. 4 shows an example of a temporal change of the absorbance ABS (λ) and the second derivative of the absorbance ABS ″ (λ). In this example, the amount of air injected into the cuff 8 by an air pump is adjusted. This is a case where the state where the venous blood flow is stopped while maintaining the arterial blood flow at the site F to be measured is obtained at the same time based on the high-speed sampling about every 10 to 20 msec as described above. Absorbance ABS (λ1),
Using ABS (λ2) and ABS (λ3), a second derivative of the absorbance ABS ”(λ) at each sampling point is obtained, and the second derivative of the absorbance ABS ″ (λ) is obtained with time in FIG. To change. In FIG. 4, (a) and (b) relate to a different measurement target (measurement site F).

In the arithmetic processing circuit 14, within a predetermined time (FIG. 4)
(From time TS to TE) at step (A), a representative value of the second derivative of the absorbance ABS ”(λ) is determined. As the representative value, the average value P [Pa in FIG. 4A or Pb in FIG. The average value P is represented by A
It is obtained by dividing a value obtained by integrating BS "(λ) for a predetermined time by a predetermined time.
The average value of the maximum value and the minimum value of (λ) can be used instead. The predetermined time may be a time equal to or more than one cycle of pulsation, but is preferably a time including several pulsations from the viewpoint of measurement accuracy. Specifically, this predetermined time is, for example, 2 to
It can be about 5 seconds, and during this predetermined time, the state where only the venous blood flow by the cuff is stopped is maintained.

As shown in FIGS. 4 (a) and 4 (b), the average value Pa,
Pb is different from each other. The difference between these averages is first
This is based on the difference in the blood sugar level of the measurement site F. The relationship between the average value P of the second derivative of the absorbance ABS ”(λ) and the blood sugar level is determined in advance as a calibration curve from the actually measured data obtained by in vitro and in vivo experiments using the least square method or the like. Fig. 5 shows the second derivative AB of the absorbance.
An example of a calibration curve of the relationship between S ″ (λ) and blood glucose level (obtained at a certain temperature [reference temperature]) is shown here by a first-order approximation based on the actual measurement values shown in the figure. The obtained linear calibration curve M1 is shown.

However, the absorbance second derivative ABS "(λ) and its average value P fluctuate when the measurement conditions, for example, the temperature of the site F to be measured fluctuate in accordance with the surrounding environment conditions. , The relationship between the average value P and the blood glucose level changes according to the temperature of the measurement site F. Therefore, in the present embodiment, it is not necessary to manage to maintain the temperature of the measurement site F constant during measurement. For this purpose, the average value P according to the temperature of the measured portion F obtained by the temperature measuring device 9 is corrected.

That is, the arithmetic processing circuit 14 calculates a temperature difference dT (= T−T ₀ ) between the temperature T of the measured portion F input from the temperature measuring device 9 and the reference temperature T _0, and calculates this temperature difference. d
A correction value C · dT is obtained by multiplying T by a temperature correction coefficient C for an average value P at a wavelength λ (= λ2) stored in advance.

FIG. 6 shows an example of the relationship between the temperature of the measured portion F and the second derivative of the absorbance obtained by a test in order to obtain the temperature correction coefficient C. Such a relationship can be obtained as follows. That is, the second derivative of the absorbance has a correlation with the temperature of the portion to be measured, and the correlation coefficient changes according to the wavelength (for example, the center wavelength among the three wavelengths) used to obtain the second derivative of the absorbance. . FIG. 7 shows this correlation diagram. A center wavelength (for example, 1000 nm) at which a large correlation coefficient is obtained in a wavelength range different from λ1, λ2, λ3.
And two wavelengths close to this center wavelength (for example, 990n
m and 1010 nm), and the relationship between the second derivative of absorbance obtained using these wavelengths and the temperature of the portion to be measured is obtained by an experiment, whereby the relationship shown in FIG. 6 is obtained. FIG. 6 shows that the second derivative of the absorbance can be approximated by a straight line E with respect to the temperature. The correction coefficient C is determined as corresponding to the inclination of this straight line.

Then, in the arithmetic processing circuit 14, FIG.
When the blood glucose level is obtained using the calibration curve, the average value of the absorbance secondary differential value ABS ″ (λ) obtained by the calculation based on the actual measurement value is used as the average value of the absorbance secondary differential value. On the other hand, the corrected average value P ′ obtained by adding the correction value C · dT is used, that is, P ′ = P + C · ΔT is obtained by the calculation, and the temperature correction corresponding to P ′ is performed using the calibration curve M1 in FIG. The blood sugar level can be obtained.

The relationship shown by the straight line E in FIG. 6 is obtained by calculating the second derivative of the absorbance at a center wavelength of 1000 nm instead of measuring the temperature of the measurement site F by the temperature measuring device 9. The temperature of the measured portion F can be obtained by performing the conversion using In this case, a light source having a light in these wavelength ranges is used as the light source 2, and a light detector 4 capable of detecting light in these wavelength ranges (in addition to the light receiving units 32-1 to 32-3). Further, a second derivative of absorbance (center wavelength: 1000 nm) may be calculated by the arithmetic processing circuit 14 using a light receiving unit having three light receiving units. According to this, the temperature measuring device 9 and the accompanying devices can be omitted.

By performing the temperature correction as described above,
A blood glucose level with a small measurement error is obtained irrespective of the temperature of the measurement site F. Therefore, it is not necessary to make an effort to keep the temperature conditions constant in order to improve the measurement accuracy, and high-accuracy blood sugar level measurement can be easily performed. Further, the arithmetic processing circuit 14 calculates the second derivative of the absorbance ABS ”(λ) at the reference temperature.
Temperature is corrected based on the calibration curve and the temperature correction coefficient of the relationship between the blood glucose level and the blood glucose level.
It is not necessary to prepare a separate calibration curve indicating the relationship between S ″ (λ) and the blood glucose level.

FIG. 8 is a flowchart of the blood sugar level measurement operation of the arithmetic processing circuit 14 as described above. That is, roughly, in the arithmetic processing circuit 14, in step S1, the absorbance AB
S (λ1) to ABS (λ3) are calculated, and a second derivative of absorbance ABS ”(λ2) is calculated in step S2, and a second derivative of absorbance ABS” (λ2) is calculated in step S3.
, A correction value C · dT of the average value P based on the difference between the detected temperature and the reference temperature is calculated in step S4, and a corrected average value P ′ is calculated in step S5. Then, in step S6, the blood glucose level is converted into a temperature-corrected blood glucose level using a calibration curve.

The operation of this embodiment is controlled by a control unit (not shown). This control is performed by controlling the operation of the arithmetic processing circuit as described above, and also by controlling the lamp 21 of the light source 2 and the semiconductor lasers 26-1 to 26-2 via the control path X in FIG.
-3 control of the light emission intensity or control of the stop 22 of the light source 2, control of the cuff pressure performed through the control path Y in FIG.
Amplifiers 10-1 and 10-1 performed via control path Z in FIG.
This is control of the amplification factors of 0-2 and 10-3.

Since there is an individual difference in the size of the portion to be measured F, the integrated value of the intensity of at least one of the transmitted lights of the wavelengths λ1, λ2, λ3 detected by the photodetector 4 for a certain time or the integrated value thereof. Wavelengths λ1, λ2, λ emitted from the light source 2 so that the time average value is close to a predetermined value.
The intensity of the light of No. 3 can be controlled via the control path X, whereby the detection conditions of the photodetector 4 can be kept constant. Note that this control may be performed first each time the measurement site F changes.

By controlling the pulsating measured portion F via the control path Y so as to apply a pressing force by the cuff 8 and detecting the transmitted light of the wavelengths λ1, λ2, λ3, the measured portion F is obtained. By fixing F, the detection condition can be kept constant.

The amplifiers 10-1 and 10-1 are connected via the control path Z.
By controlling the amplification factors of −2 and 10−3, the processing conditions of the arithmetic processing system can be set as desired.

[0045]

As described above, according to the blood sugar level measuring method and apparatus of the present invention, the representative value of the second derivative of the absorbance within a predetermined time is obtained, and the representative value is used as the reference temperature of the detected biological temperature. The temperature-corrected representative value is obtained by correcting for the deviation from the temperature, and the blood glucose level corresponding to the temperature-corrected representative value is obtained. Therefore, the occurrence of measurement errors due to temperature can be minimized, and the temperature condition is kept constant. It is possible to easily improve the measurement accuracy of the noninvasive blood glucose level measurement without performing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a blood sugar level measuring device of the present invention in which a blood sugar level measuring method according to the present invention is performed.

FIG. 2 is a schematic diagram showing a specific example of a light source in the apparatus of FIG.

FIG. 3 is a schematic diagram showing a specific example of a photodetector in the apparatus of FIG.

FIG. 4 shows absorbance values ABS obtained in the apparatus of FIG.
FIG. 9 is a diagram illustrating an example of (λ) and a second derivative of the absorbance ABS ″ (λ).

FIG. 5 is a diagram showing an example of a calibration curve of a relationship between a second derivative of absorbance ABS ″ (λ) and a blood sugar level used in the apparatus of FIG. 1;

FIG. 6 is a diagram illustrating an example of a relationship between a temperature and a second derivative of absorbance ABS ”(λ).

FIG. 7 is a diagram showing the wavelength dependence of the correlation between the second derivative of the absorbance and the temperature of the portion to be measured.

FIG. 8 is a diagram showing a blood sugar level measuring operation of the arithmetic processing circuit in the apparatus of FIG. 1;

[Explanation of symbols]

 Reference Signs List 2 light source 4 photodetector 6 portion to be measured 8 cuff 9 temperature detector 10-1 to 10-3 variable amplification rate amplifier 12-1 to 12-3 A / D converter 21 lamp 22 aperture 23 monitor 24 half mirror 25 Monitor 26-1 to 26-3 Semiconductor laser 27-1 to 27-3 Monitor 28-1, 28-2 Mirror 29-1, 29-2 Half mirror 31 Diffraction grating 32-1 to 32-3 Light receiving unit F Measurement site

Continued on the front page F term (reference) 2G045 AA01 CA25 CB30 DA31 FA12 FA25 FA29 GC10 JA01 JA02 2G059 AA01 AA05 BB12 CC16 DD01 EE01 EE11 FF04 GG01 GG03 GG05 HH01 HH06 JJ05 JJ13 JJ22 KK03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 MM03 KX02

Claims (14)

[Claims] 1. A near-infrared light having three different wavelengths and being close to each other is irradiated on a measurement site of a living body, and the intensities of the transmitted light of the three wavelengths transmitted through the measurement site are detected. A blood glucose level measuring method for determining a blood glucose level in the living body based on the transmitted light intensity detection values for the three wavelengths, wherein the temperature of the living body is detected together with the detection of the transmitted light intensities of the three wavelengths. A second derivative of the absorbance of the near-infrared light by the measured site is calculated from the transmitted light intensity detection value, a representative value of the second derivative of the absorbance within a predetermined time is obtained, and a reference value of the biological temperature detection value is obtained. A method for correcting the representative value corresponding to the deviation from the temperature, obtaining a temperature-corrected representative value, and obtaining a blood glucose value in the living body corresponding to the temperature-corrected representative value. . 2. The living body temperature detection uses a near-infrared light of three wavelengths different from the three wavelengths to obtain a second derivative of the absorbance of the measurement site, and calculates the second derivative of the absorbance. The blood glucose level measuring method according to claim 1, wherein the method is performed by performing conversion using a calibration curve. 3. The detection of the intensity of the transmitted light of the three wavelengths is performed simultaneously, and the second derivative of the absorbance is calculated based on the detected value of the transmitted light intensity obtained at the same time. 3. The blood glucose level measuring method according to any one of 2. 4. As a representative value of the second derivative of the absorbance,
Using a value obtained by dividing the value obtained by integrating the second derivative of the absorbance for a predetermined time by the predetermined time,
The blood glucose level measuring method according to claim 1. 5. As a representative value of the second derivative of the absorbance,
The blood sugar level measuring method according to any one of claims 1 to 3, wherein an average value of a maximum value and a minimum value of the second derivative of the absorbance within a predetermined time is used. 6. The apparatus according to claim 3, wherein the venous blood flow at the measurement site is stopped by applying a pressing force to the living body.
The blood glucose level measuring method according to any one of claims 1 to 5, wherein the intensity of transmitted light having two wavelengths is detected. 7. An integrated value of the intensity of at least one of the three wavelengths of transmitted light transmitted through the portion to be measured for a certain time or a time average thereof is close to a predetermined value.
The blood glucose level measuring method according to any one of claims 1 to 6, wherein the intensity of the near-infrared light of the three wavelengths incident on the measurement site is controlled. 8. Irradiating near-infrared light having three different wavelengths and approaching each other on a measured portion of a living body, detecting the intensities of the transmitted light of the three wavelengths transmitted through the measured portion, A blood sugar level measuring device for determining a blood sugar level in the living body based on the transmitted light intensity detection values for the three wavelengths, wherein: a light source that emits near-infrared light of the three wavelengths; and the three light sources emitted from the light source and transmitted through the living body. A photodetector for detecting transmitted light of three wavelengths, a temperature measuring means for detecting the temperature of the living body, and an arithmetic operation based on the transmitted light intensity detection values for the three wavelengths obtained from the photodetector. A second derivative of the absorbance of the near-infrared light by the measured portion is calculated, a representative value of the second derivative of the absorbance within a predetermined time is obtained, and a deviation of the detected biological temperature from a reference temperature is calculated. And the representative The correction to seek the temperature corrected representative value, characterized in that an arithmetic processing means for calculating a blood glucose level in said living body corresponding to the temperature corrected representative values, blood glucose measuring device. 9. The temperature measuring means uses the arithmetic processing means, and uses near-infrared light of three wavelengths different from the three wavelengths to calculate the absorbance of the part to be measured.
The blood glucose level measuring device according to claim 8, wherein the second differential value is obtained, and the temperature of the measurement site is measured by converting the second differential value of the absorbance using a calibration curve. . 10. The apparatus according to claim 8, wherein the arithmetic processing means corrects the representative value using a temperature correction coefficient in accordance with a deviation of the detected biological temperature from the reference temperature. 10. The blood glucose level measuring device according to any one of claims 9 to 9. 11. The arithmetic processing means uses, as a representative value of the second derivative of the absorbance, a value obtained by dividing a value obtained by integrating the second derivative of the absorbance for a predetermined time by the predetermined time. The blood glucose level measuring device according to any one of claims 8 to 10, wherein the blood glucose level measuring device is provided. 12. The arithmetic processing means uses an average value of a maximum value and a minimum value of the second derivative of the absorbance within a predetermined time as a representative value of the second derivative of the absorbance. The blood sugar level measuring device according to any one of claims 8 to 10. 13. The part to be measured such that an integrated value or an average of the time of the intensity of at least one of the three wavelengths of transmitted light transmitted through the part to be measured is close to the predetermined value. The blood glucose level measuring device according to any one of claims 8 to 12, further comprising: means for controlling the intensity of the near-infrared light having the three wavelengths incident on the blood glucose meter. 14. The blood glucose level measuring device according to claim 8, further comprising means for applying a pressing force to the living body.