Autonomic Nervous System Dysfunction in Patients with Type 2 Diabetes Mellitus: An Analysis Using Heart Rate Variability at University of Uyo Teaching Hospital

Cardiac autonomic neuropathy is a serious but underdiagnosed complication of type 2 diabetes mellitus, and heart rate variability offers a non-invasive means of detecting subclinical autonomic dysfunction. This study analysed autonomic nervous system function using heart rate variability parameters in type 2 diabetic patients at the University of Uyo Teaching Hospital, Akwa Ibom State, South South Nigeria. A cross-sectional analytical design recruited 75 patients with confirmed type 2 diabetes and 40 age-matched healthy controls. Five-minute resting electrocardiogram recordings were analysed for time-domain and frequency-domain heart rate variability indices, including standard deviation of normal-to-normal intervals, root mean square of successive differences, and low frequency to high frequency ratio. Duration of diabetes, glycaemic control, and presence of peripheral neuropathy symptoms were assessed as covariates. ANOVA and multiple regression were applied. Results showed significantly reduced time-domain and high-frequency heart rate variability indices in diabetic patients, indicating parasympathetic withdrawal. The low-to-high frequency ratio was elevated, suggesting sympathetic dominance. Autonomic dysfunction severity correlated positively with diabetes duration and poor glycaemic control. This study addresses a research gap on diabetic autonomic neuropathy assessment in South South Nigeria, providing preliminary normative reference data. Integration of heart rate variability screening into diabetic clinical review protocols is recommended. Keywords: cardiac autonomic neuropathy, heart rate variability, type 2 diabetes, parasympathetic function, Uyo.