Cardiac Autonomic Activity among Normal and Type 2 Diabetic Patients: A Cross-sectional Study

Introduction: Diabetic Cardiovascular Autonomic Neuropathy (DCAN) is one of the most dreaded but least recognised complications of diabetes, which manifests as a spectrum of abnormalities, ranging from resting tachycardia and decreased Heart Rate Variability (HRV) to “silent” myocardial infarction. Early identification of DCAN is essential, as timely intervention can delay or reverse autonomic dysfunction. Limited Indian data on this subject underscore the need for further research. Aim: To assess cardiovascular autonomic function in patients with Type 2 Diabetes Mellitus (T2DM) in comparison with healthy controls and also to analyse its association with age, gender, Body Mass Index (BMI), duration of diabetes, and glycaemic control. Materials and Methods: This cross-sectional study was conducted in the Department of General Medicine and Physiology at Government Medical College, Kozhikode, Kerala, India, from January 2020 to January 2021, involving 98 patients diagnosed with T2DM (diabetic group) and 98 healthy controls (control group). Cardiovascular autonomic function was assessed using a 16 channel Physiolab and PHYSIOPAC software system employing Ewing’s five standard cardiovascular reflex tests. Glycaemic parameters such as Fasting Blood Sugar (FBS), Postprandial Blood Sugar (PPBS) Random Blood Sugar (RBS), and HbA1c were also measured. Statistical analyses were performed using Statistical Package for Social Sciences (SPSS) software version 18.0, with unpaired t-tests for quantitative parameters and Chi-square tests for qualitative variables. Fischer’s-exact test was used to determine the association between various parameters. Results: The study population comprised adults aged 33-60 years, with a mean age of 50.34±6.09 years in the diabetic group and 50.84±6.55 years in the control group (p-value=0.581). Gender distribution was comparable, with 47 males and 51 females in each group (p-value=1.00). The prevalence of Cardiac Autonomic Neuropathy (CAN) was significantly higher among diabetic subjects (74.5%) compared with controls (9.2%) (p-value <0.001). Severity of CAN showed a positive correlation with age (p-value=0.002), BMI (p-value <0.001), duration of diabetes (p-value <0.001), and HbA1c (p-value <0.001), but not with gender (p-value=0.09). Parasympathetic dysfunction preceded sympathetic involvement in diabetic patients. Conclusion: T2DM is strongly associated with reduced cardiovascular autonomic function. Early detection through routine autonomic function testing, coupled with optimal glycaemic control and lifestyle modification, is recommended to prevent progression of DCAN.