A method and system for non-invasive measurement of blood glucose involving the use of Raman spectra and measurements of pulse modulated content of red blood cells in the illuminated tissue and use of phase sensitive detection reducing the impact of noise from measurement system and differences in tissues between individuals. The optoelectronic system includes an excitation laser (LR), that emits radiation passing through the Raman probe (SR) and illuminating a tissue under test (TK). The Raman scattering radiation is collected by the Raman probe (SR) and recorded by the camera (KR) after having passed through the spectrometer (SP). Simultaneously, pulse is measured by pulse oximetry (PO) in similar tissue volume of which Raman scattering radiation is recorded. For both signals the phase sensitive detection is applied, performed by the control computer (KS), wherein multiplier and a low pass filter are implemented. Phase sensitive detection enables extraction of the signal proportional to blood glucose from the Raman spectrum, reducing the noise of the measuring system and effects derived from differences in the composition of illuminated tissue caused by the variability of individual.
