Method and apparatus for noninvasively measuring a concentration of a blood component

An apparatus for noninvasively measuring a concentration of a blood component, comprising:

• a light source that emits light;
• a spectroscope that separates the light emitted from the light source into components of different wavelengths;
• a body-machine interface unit, which is adapted to be mounted on a body part of a subject, that radiates the light from the spectroscope onto the body part, collects light transmitted through the body part, varies a thickness of the body part according to a pressure applied to the body part, and secures the body part;
• a detection unit that detects a first through a fourth absorption spectrum from the light collected by the body-machine interface unit;
• and
• a signal processor that generates a signal for the body-machine interface unit to apply pressure to change the thickness of the body part, and estimates the concentration of a blood component from a second differential absorption spectrum obtained at the body part based on a multivariate statistical model of the blood component, the multivariate statistical model being established using a first differential absorption spectrum between the first and second absorption spectrums measured by the detection unit at different thicknesses of the body part and an actually measured concentration of the blood component.