Effect of local heating on couplings between cardio-respiratory and peripheral oscillations in type 2 diabetes mellitus

The investigation was aimed at studying the effects of local heating on interactions between cardio-respiratory and peripheral microvascular oscillations in patients with type 2 diabetes mellitus to develop effective methods of early diagnostics of microvascular disorders.

Heart rate variability (HRV), respiration, forearm, and foot skin blood flow (SBF) were simultaneously recorded at rest and during local heating in controls and patients. Signals were subjected to group wavelet phase coherence (gWPC) and correlation analysis. The most effective predictors of disturbances of cardiovascular interactions were determined by ROC curve analysis.

In patients, local heating decreased gWPC between HRV and SBF_forearm in high frequency; and increased gWPC between HRV and SBF_foot in high-frequency intervals and between respiration and other signals. During local heating, the number of correlating spectral components was higher for SBF_forearm/foot; the strength of correlations was lower for HRV and SBF_forearm and higher for SBF_foot than in controls. Correlations were the most effective predictors to differentiate patients from controls.

Local heating changes of local and systemic interrelations in the cardiovascular system in patients can be a good test to reveal early impairment of cardiac and vascular functions in diabetes.