Autonomic regulation in patients with diabetic neuropathy

Abstract

Cardiac and vascular damage resulting from autonomic neuropathy is a complication of diabetes that often goes undiagnosed. The aims of this study were 1) to quantify damage to cardiac and vascular function in patients diagnosed with peripheral neuropathy, and 2) to develop noninvasive measures to diagnose autonomic neuropathy.METHODSContinuous blood pressure, ECG, blood flow and respiration were monitored in 7 able‐bodied subjects (AB), 9 diabetics without (D0), and 7 diabetics with (D1), neuropathy during supine rest and 70° head up tilt (HUT). Mean values, spectral power and partial coherence analyses were used to discriminate groups.RESULTSIn response to HUT, diabetics increased heart rate to higher levels, but were unable to maintain BP as well as did AB. Low frequency spectral power of SBP and high frequency power of RRI were higher in AB than diabetics during rest and HUT. AB had the highest, and D1 the lowest, slope of baroreflex sequences during rest and HUT.CONCLUSIONSOur results support the concept that diabetes diminishes both sympathetic and parasympathetic influence on cardiac and vascular function and suggest that noninvasive indices may help discriminate patients with autonomic neuropathy. Supported by NIH RO1 NS39774, Kentucky NASA EPSCOR WKU 52611, and UK GCRC USPHS grant #M01RR02602. We acknowledge contributions of A Hartman, RN, L Krompak, L Mohney, D Silcox and R Schneider.