Blood sugar level measuring apparatus and blood sugar level measuring method

Abstract

To provide a blood sugar level measuring device and a blood sugar level measuring method capable of accurately measuring a blood sugar level.SOLUTION: The blood glucose level measurement device 1 includes the light output unit 3 that outputs the measurement light L to the living body 6, the light detection unit 4 that detects the measurement light L transmitted through the living body, the time phase difference calculation unit 51 that calculates the time phase difference based on the detection result, the blood glucose level calculation unit 52 that calculates the blood glucose level of the living body 6 based on the time phase difference, and the inertial sensor 10 that detects the body motion parameter of the living body 6. When the body motion parameter detected by the inertial sensor 10 is equal to or less than the threshold value, the blood-sugar level calculating section 52 accumulates the calculated blood-sugar level in the storing section 53.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a blood glucose level measuring device and a blood glucose level measuring method. [Background technology]

[0002] A known technique for measuring blood glucose levels in a living body is, for example, the device described in Patent Document 1. The device described in Patent Document 1 calculates the temporal phase difference between an oxygenated hemoglobin waveform related to the oxygenated hemoglobin concentration in the blood of the living body and a deoxygenated hemoglobin waveform related to the deoxygenated hemoglobin concentration in the blood of the living body based on the detection result of light transmitted through the living body.The device then noninvasively calculates the blood glucose level of the living body based on the calculated temporal phase difference. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-57511 Summary of the Invention [Problem to be solved by the invention]

[0004] The blood glucose level measuring device described above uses light to measure blood glucose levels in a living body non-invasively and accurately. However, there are cases where such blood glucose level measuring devices are required to further improve the blood glucose level measurement accuracy.

[0005] Therefore, an object of the present disclosure is to provide a blood glucose level measuring device and a blood glucose level measuring method that are capable of measuring blood glucose levels with high accuracy. [Means for solving the problem]

[0006] The blood glucose measuring device of the present disclosure is [1] "a blood glucose measuring device comprising: a blood glucose level estimation unit that outputs light to a living organism, detects the light that has passed through the living organism, calculates a temporal phase difference between an oxygenated hemoglobin waveform related to the oxygenated hemoglobin concentration in the blood of the living organism and a deoxygenated hemoglobin waveform related to the deoxygenated hemoglobin concentration in the blood of the living organism based on the detection result, and calculates the blood glucose level of the living organism based on the calculated temporal phase difference; and a body movement detection unit that detects a parameter related to the body movement of the living organism, wherein the blood glucose level calculation unit stores the calculated blood glucose level in a memory unit when the parameter detected by the body movement detection unit or a fluctuation in the parameter is equal to or less than a threshold value."

[0007] When measuring a living body's blood glucose level non-invasively using light, it is easily affected by the body's movement, and it has been found that, for example, when the body moves vigorously, the accuracy of blood glucose measurement deteriorates. Therefore, in the blood glucose measuring device described in [1] above, when the parameter detected by the body movement detection unit or its fluctuation is below a threshold, the calculated blood glucose level is stored in a memory unit. Therefore, the blood glucose level stored in the memory unit is less affected by the body's movement, and the accuracy is improved. In other words, it is possible to measure the blood glucose level of a living body with high accuracy.

[0008] The blood glucose level measuring device of the present disclosure may be [2] "the blood glucose level measuring device according to the above [1], including a metabolic information acquiring unit that acquires metabolic information related to the metabolism of the living body based on the blood glucose level of the living body stored in the memory unit." The blood glucose level measuring device according to the above [2] makes it possible to acquire metabolic information from the stored blood glucose level.

[0009] The blood glucose measuring device of the present disclosure may be the blood glucose measuring device described in [1] or [2] above, [3] "wherein the metabolic information is information about calories burned during exercise of the living body, and the metabolic information acquiring unit calculates a blood glucose excursion profile during exercise that indicates a change in actual blood glucose level based on the blood glucose level of the living body stored in the storage unit for a predetermined period from the start to the end of the exercise, estimates a blood glucose excursion profile during non-exercise that indicates a change in blood glucose level if the living body does not exercise during the predetermined period based on an initial value of the blood glucose excursion profile during exercise, estimates an external force profile that indicates a change in external force corresponding to the exercise applied during the predetermined period based on the blood glucose excursion profile during exercise and the blood glucose excursion profile during non-exercise, and estimates the calories burned based on the external force profile." The blood glucose measuring device described in [3] above can acquire calories burned during exercise of the living body as metabolic information.

[0010] The blood glucose measuring device of the present disclosure may be [4] "the blood glucose measuring device according to any one of [1] to [3] above, comprising a warning output unit that outputs a warning when the parameter detected by the body movement detection unit is equal to or lower than a threshold value and the calculated blood glucose level is higher than an upper limit, is estimated to be higher than the upper limit after a predetermined time, is lower than a lower limit, or is estimated to be lower than the lower limit after a predetermined time." The blood glucose measuring device described in [4] above can issue a warning regarding an increase or decrease in the blood glucose level of a living body.

[0011] The blood glucose measuring device of the present disclosure may be [5] "the blood glucose measuring device according to any one of [1] to [4] above, wherein the blood glucose calculating unit discards the calculated blood glucose level or assigns a low reliability label to the calculated blood glucose level when the parameter detected by the body movement detecting unit is greater than a threshold value." In the blood glucose measuring device described in [5] above, it is possible to discard or assign a low reliability label to a blood glucose level whose measurement accuracy has deteriorated due to the adverse effects of body movement and use it separately.

[0012] The blood glucose measuring device of the present disclosure may be [6] "the blood glucose measuring device according to any one of [1] to [5] above, wherein the body motion detecting unit includes an inertial sensor." In the blood glucose measuring device according to [6] above, an inertial sensor can be used as the body motion detecting unit.

[0013] The blood glucose level measuring method of the present disclosure is [7] "a blood glucose level measuring method comprising: a blood glucose level calculating step of outputting light to a living organism, detecting the light transmitted through the living organism, calculating a temporal phase difference between an oxygenated hemoglobin waveform relating to an oxygenated hemoglobin concentration in the blood of the living organism and a deoxygenated hemoglobin waveform relating to a deoxygenated hemoglobin concentration in the blood of the living organism based on the detection result, and calculating the blood glucose level of the living organism based on the calculated temporal phase difference; and a body movement detecting step of detecting a parameter relating to the body movement of the living organism, wherein in the blood glucose level calculating step, the calculated blood glucose level is stored in a memory unit if the parameter detected in the body movement detecting step is equal to or less than a threshold value." The blood glucose level measuring method described in [7] above also makes it possible to accurately measure the blood glucose level of a living organism, as with the blood glucose level measuring device described above. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a blood glucose level measuring device and a blood glucose level measuring method that are capable of calculating blood glucose levels with high accuracy. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a conceptual diagram showing a blood glucose level measuring device according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the ECU shown in FIG. [Figure 3] FIG. 3 is a graph showing an example of the detection result of the light detection unit of FIG. [Figure 4] FIG. 4 is a graph showing the waveform of oxygenated hemoglobin and the waveform of deoxygenated hemoglobin calculated from the detection results of FIG. [Figure 5]FIG. 5 is a schematic diagram showing the oxygenated hemoglobin waveform and the deoxygenated hemoglobin waveform of FIG. [Figure 6] Figure 6(a) is a graph showing the blood glucose fluctuation profile during exercise, and Figure 6(b) is a graph showing the blood glucose fluctuation profile during non-exercise. [Figure 7] Fig. 7(a) is a graph showing an external force profile, and Fig. 7(b) is a diagram for explaining calculation of calorie expenditure from the external force profile of Fig. 7(a). [Figure 8] Fig. 8(a) is a diagram showing a first example of blood glucose level information displayed on the display of Fig. 2. Fig. 8(b) is a diagram showing a second example of blood glucose level information displayed on the display of Fig. 2. Fig. 8(c) is a diagram showing a first example of a warning displayed on the display of Fig. 2. Fig. 8(d) is a diagram showing a second example of a warning displayed on the display of Fig. 2. [Figure 9] Fig. 9(a) is a diagram showing a third example of a warning displayed on the display of Fig. 2. Fig. 9(b) is a diagram showing a fourth example of a warning displayed on the display of Fig. 2. Fig. 9(c) is a diagram showing a fifth example of a warning displayed on the display of Fig. 2. [Figure 10] Fig. 10(a) is a diagram showing a first example of a warning displayed on the display of the external terminal, and Fig. 10(b) is a diagram showing a second example of a warning displayed on the display of the external terminal. [Figure 11] FIG. 11 is a flowchart showing a blood glucose level measuring method according to an embodiment. [Figure 12] FIG. 12 is another flowchart showing the blood glucose level measurement method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be omitted.

[0017] The blood glucose measuring device 1 shown in Fig. 1 is, for example, a wearable device, a smartphone, or a pulse oximeter. Examples of wearable devices include a smart watch and a smart ring. The blood glucose measuring device 1 of this embodiment is a smart watch that can be worn by a living body 6 at all times and has the function of measuring the blood glucose level of the living body 6 (the user). The living body 6 has a superficial tissue 61 and an internal tissue 62 that is located deeper inside the living body 6 than the superficial tissue 61. The surface 61a of the superficial tissue 61 is the surface of the skin of the living body 6. The living body 6 is, for example, a human body.

[0018] The blood glucose measuring device 1 measures the blood glucose level of a living organism 6. As shown in FIGS. 1 and 2, the blood glucose measuring device 1 includes a main body 2, an optical output unit 3, an optical detection unit 4, an inertial sensor 10, a display 11, a speaker 12, a vibration motor 13, and an ECU (Electronic Control Unit) 50. The main body 2 has a front face 2a and a back face 2b facing the opposite side to the front face 2a. The blood glucose measuring device 1 is worn on the living organism 6 so that the back face 2b comes into contact with the skin of the living organism 6.

[0019] The light output unit 3 is provided in the main body 2. The light output surface of the light output unit 3 is exposed from the back surface 2b of the main body 2. The light output unit 3 has a light source that outputs measurement light (light) L to the living body 6. The light source is, for example, a light emitting diode (LED), a laser diode (LD), or a superluminescent diode (SLD). The measurement light L is emitted from the back surface 2b. The measurement light L emitted from the light output unit 3 propagates inside the living body 6, and then is emitted from the living body 6 again. The light output unit 3 is controlled by the ECU 50.

[0020] The wavelength range of the measurement light L is, for example, from the red wavelength region of visible light to the near-infrared region (670 nm to 2500 nm). That is, the light output unit 3 outputs measurement light L included in the range from the red wavelength region of visible light to the near-infrared region. The light output unit 3 outputs measurement light L, for example, with different wavelengths. In this case, the light output unit 3 has multiple (for example, three) light sources. The first light source outputs measurement light L having a wavelength of, for example, 735 nm, the second light source outputs measurement light L having a wavelength of, for example, 810 nm, and the third light source outputs measurement light L having a wavelength of, for example, 850 nm. Note that the light output unit 3 may have a single light source that outputs probe light (for example, white light) containing mutually different wavelength components.

[0021] The light detection unit 4 is provided in the main body 2. The light detection unit 4 is separated from the light output unit 3. The light detection surface of the light detection unit 4 is exposed from the rear surface 2b of the main body 2. The light detection unit 4 has a light detection element that detects measurement light (transmitted light) L output from the light output unit 3 and transmitted through the living body 6. The light detection element is, for example, a photodiode (PD). The light detection unit 4 also has a preamplifier that amplifies the photocurrent output from the light detection element, and an A / D conversion circuit that converts the signal amplified by the preamplifier into a digital signal. The light detection unit 4 may have a CCD image sensor, a CMOS image sensor, or the like. The light detection unit 4 transmits a signal related to the intensity of the measurement light L to the ECU 50.

[0022] 3, the light detection unit 4 detects at least first data D1 and second data D2. The first data D1 is, for example, a change over time in the intensity of transmitted light when measurement light L having a first wavelength passes through the living body 6 and enters the light detection unit 4, and the second data D2 is, for example, a change over time in the intensity of transmitted light when measurement light L having a second wavelength passes through the living body 6 and enters the light detection unit 4. Each of the first data D1 and the second data D2 periodically fluctuates over time. Note that the respective periods of the first data D1 and the second data D2 approximately coincide with the cardiac cycle of the living body 6.

[0023] As shown in FIGS. 1 and 2, the inertial sensor 10 is provided in the main body 2. The inertial sensor 10 constitutes a body motion detection unit that detects parameters related to the body motion of the living body 6 (hereinafter simply referred to as "body motion parameters"). The inertial sensor 10 includes a triaxial acceleration sensor that detects acceleration in each of three mutually orthogonal axis directions (e.g., X, Y, and Z directions). In this case, it is possible to detect translational motion of the living body 6 in each of the three axes. Instead of or in addition to the triaxial acceleration sensor, the inertial sensor 10 may include a triaxial gyro sensor that detects angular acceleration around three mutually orthogonal axes. In this case, it is possible to detect rotational motion of the living body 6 around the three axes. The inertial sensor 10 may further include a geomagnetic sensor that detects the direction of the geomagnetic field. In this case, it is possible to detect the direction in which the blood glucose measuring device 1 is facing in an absolute coordinate system. By combining the detection results of the 3-axis acceleration sensor, 3-axis gyro sensor, and geomagnetic sensor, it becomes possible to recognize the orientation of the blood glucose measuring device 1 and the direction of movement of the living body 6 based on absolute coordinates. The inertial sensor 10 transmits a signal related to the body movement parameters to the ECU 50.

[0024] The display 11 is provided on the front face 2a side of the main body 2. The display 11 displays various information about the blood glucose measuring device 1. The display 11 here is a touch panel display that allows various settings and input / output of information. The display 11 displays information about the current or future blood glucose level of the living body 6. The display 11 displays warning messages. The display 11 is not particularly limited, and various known displays can be used.

[0025] The speaker 12 is provided in the main body 2. The speaker 12 outputs various sounds and voices. The speaker 12 also outputs warning sounds. The speaker 12 is not particularly limited, and various known speakers can be used. The vibration motor 13 is provided in the main body 2. The vibration motor 13 is a motor that generates vibrations when driven. The vibration motor 13 outputs a warning through the vibration. The vibration motor 13 is not particularly limited, and various known motors can be used. Note that the manner of warnings by at least one of the display 11, the speaker 12, and the vibration motor 13 is not particularly limited. For example, the warning may have an irregular or unstable volume and / or rhythm that intentionally induces discomfort or feelings of anxiety.

[0026] The ECU 50 is provided in the main body 2. The ECU 50 is an electronic control unit having a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ECU 50 performs various processes, for example, by having the CPU execute programs stored in the ROM or RAM. The ECU 50 calculates the pulse of the living body 6 based on the detection result of the light detection unit 4. The method for calculating the pulse is not particularly limited, and various known methods may be used. The ECU 50 calculates the blood glucose level of the living body 6 based on the detection result of the light detection unit 4 (details will be described later). The ECU 50 may be composed of a single electronic unit or multiple electronic units capable of communicating with each other. The pulse may be detected by a heart rate sensor.

[0027] The ECU 50 includes, as functional components, a temporal phase difference calculation unit 51, a blood glucose level calculation unit 52, a storage unit 53, and a metabolic information acquisition unit 54. As shown in Fig. 4, the temporal phase difference calculation unit 51 calculates an oxygenated hemoglobin waveform P1 and a deoxygenated hemoglobin waveform P2 based on the detection results of the light detection unit 4. The oxygenated hemoglobin waveform P1 is data related to the oxygenated hemoglobin (OHb) concentration in the blood of the living body 6, and the deoxygenated hemoglobin waveform P2 is data related to the deoxygenated hemoglobin (HHb) concentration in the blood of the living body 6. The temporal phase difference calculation unit 51 calculates the oxygenated hemoglobin waveform P1 and the deoxygenated hemoglobin waveform P2 by performing spectroscopic calculation processing based on, for example, the Modified Beer-Lambert (MBL) method on the first data D1 and the second data D2.

[0028] Specifically, the temporal phase difference calculation unit 51 calculates the temporal relative change in oxygenated hemoglobin (ΔO2Hb) and the temporal relative change in deoxygenated hemoglobin (ΔHHb) based on the difference between the intensity of the first data D1 at the first time and the intensity of the first data D1 at the second time (the temporal change in the intensity of the first data D1), the difference between the intensity of the second data D2 at the first time and the intensity of the second data D2 at the second time (the temporal change in the intensity of the second data D2), the respective absorption coefficients of oxygenated hemoglobin and deoxygenated hemoglobin for the first data D1, and the respective absorption coefficients of O2Hb and HHb for the second data D2. The temporal phase difference calculation unit 51 continues to calculate ΔO2Hb and ΔHHb at predetermined time intervals (for example, approximately 16 milliseconds). The change in ΔO2Hb over time is the oxygenated hemoglobin waveform P1 shown in Figure 4, and the change in ΔHHb over time is the deoxygenated hemoglobin waveform P2 shown in Figure 4. The concentration index on the vertical axis in Figure 4 is, for example, a volume concentration index (concentration × optical path length).

[0029] The temporal phase difference calculation unit 51 calculates the temporal phase difference (hereinafter simply referred to as "temporal phase difference") between the oxygenated hemoglobin waveform P1 and the deoxygenated hemoglobin waveform P2. FIG. 5 is a schematic diagram of the oxygenated hemoglobin waveform P1 and the deoxygenated hemoglobin waveform P2 shown in FIG. 4. The temporal phase difference calculation unit 51 calculates the time difference between a first characteristic point C1 of the oxygenated hemoglobin waveform P1 and a second characteristic point C2 of the deoxygenated hemoglobin waveform P2 as the temporal phase difference Δθ. In this embodiment, the first characteristic point C1 is a bottom point of the oxygenated hemoglobin waveform P1, and the second characteristic point C2 is a bottom point of the deoxygenated hemoglobin waveform P2. The first characteristic point C1 may be, for example, a peak point or a notch point of the oxygenated hemoglobin waveform P1, and the second characteristic point C2 may be, for example, a peak point or a notch point of the deoxygenated hemoglobin waveform P2. In this embodiment, the method of calculating the temporal phase difference Δθ may be, for example, one of the methods disclosed in Japanese Patent No. 6846152. The method of calculating the temporal phase difference Δθ is not particularly limited, and various known methods may be used.

[0030] The blood glucose level calculation unit 52 calculates and estimates the blood glucose level of the living organism 6 based on the temporal phase difference Δθ calculated by the temporal phase difference calculation unit 51. For example, the blood glucose level calculation unit 52 calculates the blood glucose level of the living organism 6 using the formula G=α×Δθ-β, where G is the blood glucose level of the living organism 6, Δθ is the temporal phase difference, and α and β are coefficients determined according to the glucose metabolic capacity and the measurement site of the living organism 6. In this embodiment, the blood glucose level may be calculated using, for example, the methods disclosed in Japanese Patent No. 6846152. The blood glucose level calculation method is not particularly limited, and various known methods may be used.

[0031] The blood glucose level calculation unit 52 stores the calculated blood glucose level in the storage unit 53 when the body movement parameter detected by the inertial sensor 10 or a variation in the body movement parameter is equal to or less than a threshold. The blood glucose level calculation unit 52 stores the calculated blood glucose level in chronological order in the storage unit 53 in association with time. The variation in the body movement parameter may be the amount of variation per unit time or the total amount of variation. On the other hand, when the body movement parameter detected by the inertial sensor 10 or a variation in the body movement parameter is greater than the threshold, the blood glucose level calculation unit 52 discards the calculated blood glucose level (i.e., does not store the calculated blood glucose level in the storage unit 53). The threshold may be a preset value determined from the perspective of the accuracy required for calculating the blood glucose level. The threshold may be a fixed value or a variable value that can be changed, for example, by a user input.

[0032] Note that, when the inertial sensor 10 includes multiple sensors, threshold values ​​corresponding to each of the sensors may be set. In this case, the calculated blood glucose level may be stored in the storage unit 53 when one body movement parameter or its variation detected by any of the multiple sensors included in the inertial sensor 10 is equal to or less than the threshold value. Alternatively, the calculated blood glucose level may be stored in the storage unit 53 when all of the multiple body movement parameters or their variations detected by each of the multiple sensors included in the inertial sensor 10 are equal to or less than the threshold value. Alternatively, the calculated blood glucose level may be stored in the storage unit 53 when one or more body movement parameters or their variations detected by some of the multiple sensors included in the inertial sensor 10 are equal to or less than the threshold value.

[0033] In the determination by the blood glucose level calculation unit 52, for example, if the inertial sensor 10 includes a triaxial acceleration sensor, it may determine whether all or part of the detected acceleration in each axial direction is equal to or less than a threshold. Alternatively, if the inertial sensor 10 includes a triaxial gyro sensor, it may determine whether all or part of the detected angular acceleration around each axis is equal to or less than a threshold. Alternatively, if the inertial sensor 10 includes a geomagnetic sensor, it may determine whether the detected change in direction is equal to or less than a threshold.

[0034] The memory unit 53 stores various types of information. As described above, the memory unit 53 stores and accumulates the blood glucose level of the living organism 6 calculated by the blood glucose level calculation unit 52 in association with time. The metabolic information acquisition unit 54 acquires metabolic information related to the metabolism of the living organism 6 based on the blood glucose level accumulated in the memory unit 53. The metabolic information is information related to calories burned during exercise by the living organism 6. An example of a method for estimating and acquiring calories burned during exercise by the living organism 6 using the metabolic information acquisition unit 54 will be described in detail below.

[0035] First, fluctuations in blood glucose levels in a living organism 6 are modeled as the displacement of a mass damper system PID-controlled by the autonomic nervous system. Exercise and oral intake are treated as external forces applied to the model. In PID control, appropriate control can be obtained by adjusting the coefficients of the proportional term, the differential term, and the integral term.

[0036] Next, a blood glucose excursion profile K1 during exercise (see FIG. 6(a)) showing the actual change in blood glucose level is calculated based on the blood glucose levels of the living body 6 accumulated in the memory unit 53 during a predetermined period from the start to the end of exercise. Using the initial value of the blood glucose excursion profile K1 during exercise, the above-mentioned model is used to estimate a blood glucose excursion profile K2 during non-exercise (see FIG. 6(b)) showing the change in blood glucose level when no exercise is performed during a predetermined period (i.e., when no external force is applied). In the example shown in the figure, the above-mentioned model is applied to estimate the blood glucose excursion profile K2 during non-exercise under the condition that the initial value is 120 g / dL, the same as the initial value of the blood glucose excursion profile K1 during exercise, and there is no external force.

[0037] Next, based on the blood glucose excursion profile K1 during exercise and the blood glucose excursion profile K2 during non-exercise, an external force profile K3 (see FIG. 7(a)) is estimated, which indicates the transition of the external force corresponding to the exercise applied over a predetermined period. Specifically, the deviation of the blood glucose excursion profile K2 during non-exercise from the blood glucose excursion profile K1 during exercise (within the dashed circle in FIG. 6(a)) is determined, and the profile of the external force that realizes this deviation is estimated by back-calculation as the external force profile K3. Then, the calories burned are estimated based on the external force profile K3. Specifically, the integral value of the external force profile K3 (the hatched area in FIG. 7(b)) is calculated as the calories burned.

[0038] When the body movement parameter detected by the inertial sensor 10 or its variation is equal to or less than a threshold, the ECU 50 displays blood glucose level information relating to the blood glucose level calculated by the blood glucose level calculation unit 52 on the display 11. For example, as shown in FIG. 8(a), the ECU 50 may display a numerical value of the blood glucose level as the blood glucose level information in a part of the display 11. The display may be updated at specified time intervals or when the blood glucose level crosses a threshold.

[0039] 8(b), the ECU 50 may display, as blood glucose level information, an arrow indicating the current direction of blood glucose level fluctuation on the display 11. The current direction of blood glucose level fluctuation can be estimated based on the time fluctuation of blood glucose levels stored in the memory unit 53. The arrow indicating the direction of blood glucose level fluctuation may be divided into stages, such as rapid rise, rise, steady transition, fall, and rapid fall.

[0040] When the body movement parameter or its variation detected by the inertial sensor 10 is equal to or less than a threshold and the calculated blood glucose level is higher than the upper limit, is estimated to become higher than the upper limit after a predetermined time, is lower than the lower limit, or is estimated to become lower than the lower limit after a predetermined time, the ECU 50 outputs a warning via at least one of the display 11, the speaker 12, and the vibration motor 13. The upper limit and the lower limit may be preset values ​​corresponding to hyperglycemic symptoms and hypoglycemic symptoms. The upper limit and the lower limit may be fixed values ​​or may be variable values ​​that can be changed, for example, by a user input.

[0041] For example, as shown in Fig. 8(c), when the body movement parameter or its variation detected by the inertial sensor 10 is equal to or less than a threshold and the calculated blood glucose level is higher than an upper limit, the ECU 50 may cause the display 11 to display a warning message indicating that the blood glucose level is high. Also, for example, as shown in Fig. 8(d), when the body movement parameter or its variation detected by the inertial sensor 10 is equal to or less than a threshold and the calculated blood glucose level is estimated to become lower than a lower limit after a predetermined time, the ECU 50 may cause the display 11 to display a warning message indicating that the blood glucose level will become low. The blood glucose level after the predetermined time may be estimated based on the time variation of the blood glucose level accumulated in the memory unit 53.

[0042] 9(a), when the body movement parameter or its variation detected by the inertial sensor 10 is equal to or less than a threshold value and the calculated blood glucose level is higher than the upper limit, the ECU 50 may display the blood glucose level on the display 11 in a color different from that used when the blood glucose level is within the normal range or is lower than the lower limit. Note that when the body movement parameter or its variation detected by the inertial sensor 10 is equal to or less than a threshold value and the calculated blood glucose level is lower than the lower limit, the ECU 50 may display the blood glucose level on the display 11 in a color different from that used when the blood glucose level is within the normal range or is higher than the upper limit.

[0043] 9(b), the ECU 50 may display a progress bar or a meter on the display 11 in addition to the display of FIG. 9(a). Also, as shown in FIG. 9(c), the ECU 50 may display a warning message on the display 11 so that the message flashes at maximum brightness when the body movement parameter detected by the inertial sensor 10 or its variation is equal to or less than a threshold and the calculated blood glucose level is lower than a lower limit (particularly when there is a risk of hunger knock). In this case, the ECU 50 may output a loud warning sound from the speaker 12. Furthermore, in this case, the ECU 50 may drive the vibration motor 13 to generate vibrations.

[0044] In this embodiment, as described above, the blood glucose level information and the warning are output via at least one of the display 11, the speaker 12, and the vibration motor 13. However, the ECU 50 may communicate with an external terminal to output the blood glucose level information and the warning via the external terminal. For example, when the body motion parameter detected by the inertial sensor 10 or its variation is equal to or less than a threshold value and the calculated blood glucose level is higher than an upper limit, the ECU 50 may display a pop-up display PU on the display 111 of the external terminal 100, such as a smartphone, to warn that the blood glucose level is high, as shown in Fig. 10(a).

[0045] 10(b), for example, when the body movement parameter detected by the inertial sensor 10 or its variation is equal to or less than a threshold value and the calculated blood glucose level is lower than a lower limit (particularly when there is a risk of hunger knock), the ECU 50 may cause the display 111 of the external terminal 100 to display a warning message WM so that it blinks at maximum brightness. In this case, the ECU 50 may output a loud warning sound from the speaker of the external terminal 100. Furthermore, in this case, the ECU 50 may cause the external terminal 100 to vibrate.

[0046] Next, the blood glucose level measuring method of this embodiment will be described.

[0047] When the living body 6 starts exercising and the exercise mode trigger is turned ON, the blood glucose measuring device 1 of this embodiment executes the following steps related to the exercise mode, as shown in Fig. 11. Note that the ON and OFF of the exercise mode trigger may be detected automatically based on body movement parameters detected by the inertial sensor 10, for example, or may be detected by manual input via the display 11, which is a touch panel display, or the like.

[0048] In the exercise mode, first, the blood glucose level of the living body 6 is calculated (step S1). In step S1, the light output unit 3 outputs measurement light L to the living body 6, the light detection unit 4 detects the measurement light L that has passed through the living body 6, the temporal phase difference calculation unit 51 calculates a temporal phase difference Δθ based on the detection result, and the blood glucose level calculation unit 52 calculates the blood glucose level of the living body 6 based on the temporal phase difference Δθ.

[0049] Next, the inertial sensor 10 detects a body movement parameter, and the blood glucose level calculation unit 52 determines whether the body movement parameter or its fluctuation is equal to or less than a threshold (step S2). If the result in step S2 is NO, the blood glucose level calculated by the blood glucose level calculation unit 52 is discarded (step S3). Then, the process proceeds to step S7, which will be described later.

[0050] On the other hand, if the answer is YES in step S2, the blood glucose level calculated by the blood glucose level calculation unit 52 is stored and accumulated in the memory unit 53 (step S4). It is determined whether the blood glucose level calculated by the blood glucose level calculation unit 52 is lower than the lower limit (step S5). In step S5, instead of or in addition to determining whether the blood glucose level calculated by the blood glucose level calculation unit 52 is lower than the lower limit, it may determine at least one of whether the blood glucose level is higher than the upper limit, whether it is estimated to become higher than the upper limit after a predetermined time, and whether it is estimated to become lower than the lower limit after a predetermined time.

[0051] If the answer is YES in step S5, a warning is output via at least one of the display 11, speaker 12, and vibration motor 13 (step S6). Then, the exercise mode is terminated. If the answer is NO in step S5 or after step S3, it is determined whether the exercise mode trigger is OFF (step S7). If the answer is NO in step S7, the process returns to step S1, and the blood glucose level is calculated again at a predetermined interval. If the answer is YES in step S7, the exercise mode is terminated.

[0052] After executing the exercise mode described above, the blood glucose measuring device 1 of this embodiment executes the following steps related to the calorie expenditure estimation process, as shown in Fig. 12. First, the metabolic information acquiring unit 54 acquires a blood glucose excursion profile K1 during exercise based on the blood glucose levels of the living body 6 stored in the memory unit 53 during a predetermined period from the start to the end of the exercise mode (step S11). The metabolic information acquiring unit 54 then acquires a blood glucose excursion profile K2 during non-exercise using the above-described model based on the initial value of the blood glucose excursion profile K1 during exercise (step S12).

[0053] Next, the metabolic information acquisition unit 54 acquires an external force profile K3 based on the exercise blood glucose fluctuation profile K1 and the non-exercise blood glucose fluctuation profile K2 (step S13). Then, the metabolic information acquisition unit 54 estimates calories burned based on the external force profile K3 (step S14). The estimated calories burned are displayed on the display 11, for example. This completes the calorie burned estimation process.

[0054] Incidentally, when measuring the blood glucose level of a living organism 6 non-invasively using light, it is easily affected by the body movement of the living organism 6, and it has been found that the accuracy of blood glucose level measurement deteriorates when the body movement of the living organism 6 is intense. Therefore, in the blood glucose measuring device 1 and blood glucose measuring method, when the body movement parameter detected by the inertial sensor 10 or its fluctuation is below a threshold, the calculated blood glucose level is stored in the memory unit 53. Therefore, the blood glucose level stored in the memory unit 53 is less affected by the body movement of the living organism 6, and the accuracy is improved. In other words, it is possible to measure the blood glucose level of the living organism 6 with high accuracy.

[0055] The blood glucose level measuring device 1 includes a metabolic information acquiring unit 54 that acquires metabolic information of the living body 6 based on the blood glucose level stored in the storage unit 53. In this case, it is possible to acquire metabolic information from the stored blood glucose level.

[0056] In the blood glucose level measuring device 1, the metabolic information acquiring unit 54 calculates a blood glucose excursion profile K1 during exercise, estimates a blood glucose excursion profile K2 during non-exercise, and estimates an external force profile K3 based on the blood glucose excursion profile K1 during exercise and the blood glucose excursion profile K2 during non-exercise.The metabolic information acquiring unit 54 then estimates the calories burned during exercise of the living body 6 based on the external force profile K3.In this case, the calories burned can be acquired as metabolic information.

[0057] In the blood glucose measuring device 1, when the body movement parameter or its fluctuation detected by the inertial sensor 10 is equal to or less than the threshold value, and the calculated blood glucose level is higher than the upper limit, is estimated to become higher than the upper limit after a predetermined time, is lower than the lower limit, or is estimated to become lower than the lower limit after a predetermined time, a warning is output by at least one of the display 11, the speaker 12, and the vibration motor 13. In this case, a warning regarding an increase or decrease in the blood glucose level of the living body 6 can be issued.

[0058] In the blood glucose level measuring device 1, the blood glucose level calculation unit 52 discards the calculated blood glucose level when the body movement parameter detected by the inertial sensor 10 or its fluctuation is greater than a threshold value. In this case, it becomes possible to discard blood glucose levels whose measurement accuracy has deteriorated due to the adverse effects of body movement. The blood glucose level measuring device 1 is equipped with the inertial sensor 10. This allows the inertial sensor 10 to be used as a body movement detection unit that detects parameters related to the body movement of the living body 6.

[0059] In the above, the light output unit 3, the light detection unit 4, the temporal phase difference calculation unit 51, and the blood glucose level calculation unit 52 correspond to the blood glucose level estimation unit. The display 11, the speaker 12, and the vibration motor 13 correspond to the warning output unit. Steps S1, S3, and S6 correspond to the blood glucose level estimation step, and step S2 corresponds to the body movement detection step.

[0060] As described above, one aspect of the present disclosure is not limited to the above embodiment.

[0061] In the above embodiment, when the body movement parameter detected by the inertial sensor 10 is greater than a threshold, instead of discarding the calculated blood glucose level, the calculated blood glucose level may be assigned a low reliability label and stored in the storage unit 53. In this case, it is possible to distinguish and use the blood glucose level calculation results whose measurement accuracy has deteriorated due to the adverse effects of body movement of the living body 6 by referring to the low reliability label. For example, the calculated blood glucose levels may be assigned appropriate weights based on the low reliability labels and used as a population when calculating a representative value.

[0062] In the above embodiment, steps S1 to S7 are executed in the exercise mode, but this is not limiting. For example, steps S1 to S7 may be executed while the living body 6 is operating a transport device (for example, while driving a car), or may be executed periodically at a fixed cycle, or may be executed in response to a trigger operation by the living body 6, or may be executed constantly.

[0063] In the above embodiment, when a warning is output via at least one of the display 11, the speaker 12, and the vibration motor 13, foods that should be ingested to suppress hypoglycemic symptoms or hyperglycemic symptoms may be displayed on the display 11. In the above embodiment, when a warning is output via at least one of the display 11, the speaker 12, and the vibration motor 13, an alert may be sent to a pre-designated administrator terminal or the like.

[0064] In the above embodiment, the metabolic information is not limited to calories burned during exercise, but may be information regarding the exercise intensity of the exercise. The metabolic information may also include other information regarding health conditions. In the above embodiment, the ECU 50 is provided in the main body 2, but the ECU 50 does not have to be provided in the main body 2, and may be provided, for example, in a server or the like that can communicate with the main body 2. In the above embodiment, the light output unit 3 may include a broadband light source. For example, a white LED or the like is used as the broadband light source. When the light output unit 3 includes a broadband light source in this way, the light detection unit 4 may include a spectroscope.

[0065] The components in the above-described embodiment and modified examples are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the components in the above-described embodiment and modified examples can be arbitrarily applied to the components in other embodiments or modified examples. [Explanation of symbols]

[0066] 1...blood glucose measuring device, 3...light output unit (estimation unit), 4...light detection unit (estimation unit), 6...biological body, 10...inertial sensor (body movement detection unit), 11...display (warning output unit), 12...speaker (warning output unit), 13...vibration motor (warning output unit), 51...temporal phase difference calculation unit (estimation unit), 52...blood glucose calculation unit (estimation unit), 53...memory unit, 54...metabolic information acquisition unit, K1...blood glucose fluctuation profile during exercise, K2...blood glucose fluctuation profile during non-exercise, K3...external force profile, L...measurement light (light).

Claims

1. a blood glucose level estimation unit that outputs light to a living body, detects the light that has passed through the living body, calculates a temporal phase difference between an oxygenated hemoglobin waveform relating to an oxygenated hemoglobin concentration in the blood of the living body and a deoxygenated hemoglobin waveform relating to a deoxygenated hemoglobin concentration in the blood of the living body based on the detection result, and calculates a blood glucose level of the living body based on the calculated temporal phase difference; a body movement detection unit that detects parameters related to body movement of the living body, The blood glucose level estimating unit stores the calculated blood glucose level in a memory unit when the parameter detected by the body movement detecting unit or a variation in the parameter is equal to or less than a threshold value.

2. The blood glucose measuring device according to claim 1 , further comprising a metabolic information acquiring unit that acquires metabolic information relating to the metabolism of the living body based on the blood glucose level of the living body stored in the storage unit.

3. The metabolic information is information about calories burned or exercise intensity of the exercise of the living body, The metabolic information acquisition unit calculating a blood glucose fluctuation profile during exercise that indicates a transition of actual blood glucose levels based on the blood glucose levels of the living body stored in the storage unit during a predetermined period from the start to the end of the exercise; estimating a non-exercise blood glucose excursion profile that indicates a change in blood glucose level when no exercise is performed during the predetermined period based on the initial value of the exercise blood glucose excursion profile; estimating an external force profile that indicates a transition of an external force corresponding to the exercise applied during the predetermined period based on the blood glucose fluctuation profile during exercise and the blood glucose fluctuation profile during non-exercise; The blood glucose level measuring device according to claim 2 , wherein the calorie expenditure or exercise intensity is estimated based on the external force profile.

4. 3. The blood glucose measuring device according to claim 1, further comprising a warning output unit that outputs a warning when the parameter detected by the body movement detection unit or the fluctuation of the parameter is below a threshold value, and the calculated blood glucose level is higher than an upper limit value, is estimated to be higher than the upper limit value after a predetermined time, is lower than a lower limit value, or is estimated to be lower than the lower limit value after a predetermined time.

5. 3. The blood glucose measuring device according to claim 1, wherein the blood glucose level estimation unit discards the calculated blood glucose level or assigns a low reliability label to the calculated blood glucose level when the parameter detected by the body movement detection unit or a fluctuation in the parameter is greater than a threshold value.

6. The blood glucose measuring device according to claim 1 , wherein the body movement detecting unit includes an inertial sensor.

7. a blood glucose level estimation step of outputting light to a living body, detecting the light transmitted through the living body, calculating a time phase difference between an oxygenated hemoglobin waveform relating to an oxygenated hemoglobin concentration in the blood of the living body and a deoxygenated hemoglobin waveform relating to a deoxygenated hemoglobin concentration in the blood of the living body based on the detection result, and calculating a blood glucose level of the living body based on the calculated time phase difference; a body movement detection step of detecting a parameter related to the body movement of the living body, In the blood glucose level estimation step, if the parameter detected in the body movement detection step or a variation in the parameter is equal to or less than a threshold, the calculated blood glucose level is stored in a memory unit.

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