Patent ID: 7438855

Claim:
An apparatus for measuring glucose concentration, the apparatus comprising: a device to detect an absorption spectrum in a mid-infrared region corresponding to each of a plurality of samples of a patient multiple times over a time period, the device configured to conduct optical measurements on the patient, in order to obtain a calibration curve; a device to calculate the glucose concentration of each of the samples from said absorption spectra; a device to produce a covariance matrix based on the plurality of absorption spectrums; a device to obtain a plurality of eigenvectors having a relatively large eigenvalue from the covariance matrix, and set these as the spectrum loading vectors for principal component analysis; a device to take the inner product of the absorption spectrums of each of the samples and the plurality of spectrum loading vectors and obtain a plurality of spectrum score vectors of principal component analysis corresponding to each of the spectrum loading vectors; a device to obtain from among the plurality of spectrum score vectors, the single spectrum score vector in that each of the components have the best correlative relationship to the plurality of glucose concentrations measured; a device to store the relationship of the spectrum score vector and the glucose concentration as a calibration curve, and store the single spectrum loading vector corresponding to the spectrum score vector; a device to read the calibration curve; and a device to determine a glucose concentration of an sample as the detected result based on the computed spectrum score and the calibration curve.