Analysis of Oscillatory Processes in the Cardiovascular System in Response to Local Heating in Patients with Type 2 Diabetes Mellitus

A comprehensive spectral analysis of heart rate variability and skin perfusion of the extremities in patients with type 2 diabetes mellitus in response to local heating and identification of significant predictors of pathophysiological changes in the cardiovascular system has been carried out. Electrocardiogram and skin perfusion on the forearm and foot were measured by laser Doppler flowmetry at rest and under local heating in healthy individuals and diabetic patients. The signals of laser Doppler flowmetry and heart rate variability (according to electrocardiographic data) were subjected to wavelet analysis. Receiver operating characteristic analysis was used to evaluate significant predictors. It was found that in patients, compared with healthy individuals, there was (1) a decrease in the reserve of cutaneous blood flow on the foot under heating, (2) a decrease in the amplitudes of heart rate oscillations at rest and under heating, (3) an increase in the amplitudes of oscillations of laser Doppler flowmetry signals on the forearm in respiratory intervals and cardiac intervals at rest and under heating, and (4) a decrease in the amplitudes of oscillations of laser Doppler flowmetry signals on the foot in the myogenic interval at rest and in the cardiac interval under heating. The parameters of the cardiovascular system (the energy of heart rate variability in the low frequency interval and oscillations of laser Doppler flowmetry signals on the forearm in respiratory interval, which can serve as markers for early diagnosis of microvascular disorders) with high discriminatory power to distinguish patients and healthy individuals in response to local heating were revealed.