The invention relates to registering changes in vascular tone during and after a functional load, and processing data using spectral analysis methods within the frequency ranges of endothelial (0.0095-0.02 Hz), neurogenic (0.02-0.05 Hz), and myogenic (0.05-0.14 Hz) regulation mechanisms. Furthermore, the temperature of an area of a patients skin is continuously registered. During the first 1-2 minutes, the temperature of the examined skin surface is increased to 38-42° C., and the heating power is fixed. Temperature fluctuations are registered over the course of 10 minutes The heater is shut-off. Over the course of 10 minutes following the shut-off and a decrease in temperature to 30-32° C., temperature fluctuations continue to be registered, and the obtained values are compared, with coefficients being calculated for the relative change in the amplitudes of the temperature fluctuations, which are then used for determining the existence of a disorder in a vascular tone regulation mechanism.