ИСТИНА

Monitoring of glycemic status of patients with diabetes is considered a cornerstone of their care. Currently, control of this disease involves several times a day finger puncture to obtain a blood sample for chemical analysis of glucose level. This procedure is invasive, painful, non-safe and unpleasant for patients. In the past decades much attention has been paid to the development of spectroscopic methods for noninvasive glucose measuring. In our work studies of human skin reflection spectra were performed in vivo using terahertz (THz) time-domain spectroscopy in 0.1-2.0 THz frequency range. The experiments were based on the attenuated total internal reflection optical scheme with silicon right angle Dowe prism. The volunteers pushed their palm to the prism base for 3 minutes to obtain reflection spectra.. The measurements were carried out on 6 volunteers. They were in good health and have a normal blood glucose concentration (< 6.1 mM). A standard oral glucose tolerance test using 75 g glucose was performed in all volunteers. The reflection spectra of palm skin were measured at 0-120 min after intake glucose. The blood glucose concentration was determined by a commercial glucometer "OneTouch Ultra" (USA). It is shown that the most pronounced difference in the complex reflection spectra R are observed in the frequency range of 0.1-0.5 THz. Amplitude and phase of the reflection coefficient of human palm skin are changed when the blood glucose concentrations rise above the normal levels. Moreover, changes in the phase of R are more pronounced. These variations of the optical characteristics of the human skin correlate with the changes in blood glucose level and can be used as practical biophysical marker of blood state. Our results demonstrate a possibility of non-invasive real time measurement of blood glucose concentration.