Background: There are plenty of studies available to demonstrate the effect of diabetes on short-term Heart Rate Variability (HRV) but not enough about lipids, especially in our region. Hence, we aimed to study the influence of total cholesterol and individual lipid fractions on short-term HRV in type 2 diabetics. Methods: As per the set criteria, 70 newly diagnosed type 2 diabetics were recruited and grouped based on their cholesterol levels. Both the time domain and the frequency domain measures of short-term HRV were acquired and subjected to statistical analysis. This was a cross-sectional observational study. Results: Elevated total cholesterol group showed a reduction in Standard deviation of all NN intervals (SDNN) and High Frequency (HF) power and an increase in Low-Frequency power / High-Frequency power (LF/HF) ratio in comparative analysis. Similarly, the high low-density lipoproteins (LDL) group showed a decrease in square root of the mean of the sum of the squares of the differences between adjacent NN intervals (SDNN) and RMSSD but a rise in LF/HF ratio. Moreover, total cholesterol is negatively correlated with SDNN, RMSSD, and HF power while total cholesterol and LDL are positively correlated with LF/HF ratio. Total cholesterol, LDL, and triglycerides had an independent association with HF. Conclusions: Our study shows higher levels of total cholesterol, LDL and triglycerides decrease cardiovagal activity. Hence, based on this we conclude abnormal lipid levels depress HRV.

INTRODUCTIONThe magnitude of non-communicable diseases (cardiovascular diseases, diabetes, malignancies and chronic respiratory diseases) has brought about a negative socioeconomic impact and sufferings to the mankind. 1 36 million deaths have been reported every year due to diabetes and its complications. Moreover, 9 million people succumb to death prematurely.2 Improved and effective medications have increased the lifespan of diabetic population. Hence there is a need to identify and intervene at the earliest in order to prevent complications and provide them a better quality of living. Microalbuminuria is considered as an early marker. It ABSTRACT Background: Microalbuminuria is considered as an early marker and strongly associated with risk of cardiovascular complications in diabetic patients. Autonomic imbalance due to micro vascular damage to parasympathetic and sympathetic fibers results in reduced heart rate variability; also predicts increased risk for cardiovascular events in diabetics. Hence it is necessary to identify an early and effective predictor of diabetic micro vascular complications. Objective of the study was to compare heart rate variability of controls with type 2 diabetes with and without microalbuminuria. Methods: This comparative study was conducted among individuals without diabetes, hypertension and dyslipidemia (controls) and Type II diabetics with and without microalbuminuria (cases). Cases and controls were subjected to general clinical examination; microalbuminuria and HbA1C were noted. heart rate variability was assessed using digital physiograph. Frequency (HF, LF, LF/HF ratio) domain readings were noted. Results: Mann Whitney U test was employed to analyze nonparametric data. Diabetics with microalbuminuria when compared with controls showed statistically significant (p-value=0.015) reduction in vagal activity. When compared with diabetics without microalbuminuria (180.4±151.7) they showed reduction in HF with no statistical significance. When diabetic group without microalbuminuria (0.56±0.31) was compared with controls they showed alternation in LF/HF ratio which has no statistical significance. Diabetics with microalbuminuria when compared with controls showed a statistically significant (p-value=0.009) alternation in LF /HF ratio implying an autonomic imbalance. Conclusions: This study shows there is significant vagal inhibition and autonomic imbalance in diabetic patients with microalbuminuria compared to controls. To ascertain the role of HRV as an early predictor of cardiovascular complications we propose to conduct study with a larger sample size in future.