Patent ID: 7863049

Claim:
A noninvasive blood sugar level measurement method including obtaining a correlation for respective individuals between a blood sugar level of a biological body and a biological feature amount that is obtained by performing noninvasive measurement, said process of obtaining the correlation for the respective individuals comprising: varying the blood sugar level of the biological body; measuring the biological feature amount by temporally performing plural times of noninvasive measurements at first time intervals within a predetermined period, after varying the blood sugar level of the biological body; measuring the blood sugar level of the biological body by temporally performing invasive blood sugar measurements at second time intervals which are not synchronized with said first time intervals and are longer than said first time intervals within the predetermined period, the number of times of which is less than that of the noninvasive measurements, after varying the blood sugar level of the biological body; obtaining an approximate curve indicating temporal change in the blood sugar level in the predetermined period from the blood sugar level of the biological body which is obtained by the invasive blood sugar measurement; obtaining, using the approximate curve, blood sugar levels (hereinafter referred to as interpolation blood sugar levels) which are supposed to be obtained by the invasive blood sugar measurements corresponding to the respective times at which the noninvasive measurements were performed; associating the biological feature amounts which are obtained at the respective times of the noninvasive measurements with the obtained interpolation blood sugar levels, thereby forming a correlation table having plural sets of the biological feature amounts and the interpolation blood sugar levels; and eliminating the interpolation blood sugar level values in a range in which the biological feature amounts vary monotonously, with the remaining interpolation blood sugar level values in a range in which the biological feature amounts vary irregularly, measuring current biological feature amounts by performing noninvasive measurement, extracting two biological feature amounts which are between the current biological feature amounts from the correlation table in which the interpolation blood sugar levels are eliminated, and calculating the interpolation blood sugar levels from the ratio between the current biological feature amounts and the two biological feature amounts to obtain the current estimated blood sugar level.