Association Between Cardiac Autonomic Function and Peripheral Nerve Conduction Abnormalities in Type 2 Diabetes Mellitus: A Cross-Sectional Study

Background: Cardiac autonomic neuropathy and diabetic peripheral neuropathy often develop early in type 2 diabetes mellitus (T2DM) and may remain clinically silent. Heart rate variability (HRV) and nerve conduction studies (NCS) are noninvasive tools that assess autonomic and peripheral nerve function, respectively. Their relationship in early-stage T2DM is not well defined. Methods: This cross-sectional study included 100 patients with T2DM of less than five years’ duration (age 30-50 years) and 100 age- and sex-matched healthy controls. Five-minute resting HRV recordings were analyzed for time- and frequency-domain parameters. Motor and sensory NCS were performed for the median, posterior tibial, and sural nerves. Group comparisons, correlation analysis, and multivariable regression were conducted to evaluate associations and predictors of HRV impairment. Results: T2DM patients demonstrated significantly reduced parasympathetic HRV indices, including root mean square of successive differences and high-frequency (HF) power (p ≤ 0.001), along with reduced sensory and motor nerve amplitudes, most prominently sural SNAP amplitude (p < 0.001). HRV parameters showed positive correlations with NCS measures, with the strongest association observed between HF power and sural SNAP amplitude (r = 0.62). Multivariable regression identified higher glycated hemoglobin and longer diabetes duration as independent predictors of reduced HRV, while age, sex, and body mass index were not significant. Conclusions: Early-stage T2DM is associated with parallel autonomic and peripheral nerve dysfunction. HRV correlates with nerve conduction abnormalities, suggesting shared pathophysiology. Poor glycemic control and longer disease duration independently predict autonomic impairment, highlighting the importance of early metabolic control and combined neurophysiological assessment for detecting subclinical neuropathy.