Introduction: Cardiac autonomic neuropathy (CAN) is a frequent and intractable complication of diabetes. Reduction in heart rate variability (HRV) is the first sign of CAN in its subclinical stage. Autonomic imbalance and hyperglycaemia in diabetes are associated with cardiovascular structural and functional modifications which lead to left ventricular hypertrophy (LVH). The study was undertaken to assess the changes in HRV and left ventricular mass in type 2 diabetes mellitus (T2DM) patients.

Material and methods: The case-control study was conducted on 78 T2DM subjects and 78 age & sex-matched healthy controls. CAN was assessed by frequency and time-domain parameters of HRV and LVH was measured using various ECG criteria including Cornell voltage, Cornell product, Sokolow-Lyon voltage, and Romhilt-Estes point score.

Results: All the frequency and time-domain parameters of HRV except resting heart rate, normalized LF, and LF/HF ratio were significantly reduced in T2DM patients compared to healthy controls. The prevalence of ECG-LVH was 25.7% using any single criteria and 12.2% with all the criteria. The highest prevalence (24.3%) was noted with Cornell product and Sokolow-Lyon voltage criteria followed by Romhilt-Estes point score (17.6%), and Cornell voltage criteria (16.2%).

Conclusion: Reduction in overall HRV with less high-frequency power and high LF/HF ratio are suggestive of parasympathetic dysfunction and sympathetic predominance. A significant LVH was noted with ECG-based electric criteria in T2DM patients. The study suggests that T2DM patients should be subjected to diagnostic HRV and ECG to identify the early occurrence of CAN and LVH.

Keywords: Cardiovascular autonomic neuropathy; Heart rate variability; Left ventricular hypertrophy; Type 2 diabetes mellitus.