Preliminary study of mechanism of non-invasive blood glucose measurement based on near-infrared diffuse reflectance spectroscopy

Non-invasive glucose measurement by near-infrared spectroscopy is mainly based on the absorption of glucose. However, for non-invasive blood glucose measurement, the diffuse reflectance spectra are influenced not only by the absorption coefficient, but also by the scattering coefficient, anisotropy factor, and refractive index, which are normally nonlinear with the glucose concentrations. Further more, the variations of spectra depend on the relative changing direction of the absorption coefficient and scattering coefficient. In this paper, using the simulated samples of human tissues with different glucose concentrations in different conditions, we discussed the rules of how the glucose concentrations affected the absorption coefficient and scattering coefficient, respectively. The relations between the diffuse reflectance spectra and the absorption coefficient, as well as and the scattering coefficient were also investigated. Thus, we confirmed which of the optical parameters and measurement conditions would affect the diffuse reflectance spectra significantly. Based on the above results, proper methods could be selected to measure blood glucose concentration non-invasively according to different conditions, their the information of glucose absorption would be extracted more effectively, and higher measurement precision would be expected.