Relationship between Insulin Resistances with Autonomic Functions in Patients with Type 2 Diabetes in South Indian Population

Cardiovascular disease (CVD) and type 2 diabetes mellitus (T2D) are major health concerns In India. Insulin resistance (IR) itself is a risk factor for CVD. Though it is associated to sympathetic activity this relation may get altered in presence of obesity. Therefore, in the present study we measured the link of IR, with their body mass index (BMI) and the corresponding degree of alteration in various autonomic function tests in T2D patients. It was an observational study conducted in a tertiary care hospital for a period of six months. Eighty-five T2D patients visiting medicine OPD were recruited out of which 17 were normal, 31 were overweight and 31 were obese as per WHO criteria of obesity. Their glucose, insulin, insulin resistance was analyzed in fasting blood samples. Conventional autonomic function tests such as isometric hand-grip test and deep breathing test was digitally recorded. Heart rate variability was recorded as LF: HF ratio. The Rate-pressure product (RPP), the marker of myocardial work stress was calculated from systolic blood pressure and basal heart rate. E: I ratio was calculated from RR interval from ECG tracing. Insulin resistance was positively associated with increased basal heart rate. It was linked to increase LF: HF ratio even after controlling for BMI. Regression analysis showed insulin resistance to be an independent factor for sympathovagal imbalance in T2D patients. The severity of insulin resistance independently predicts degree of deterioration in sympathovagal imbalance as measured in LF: HF ratio in our study which is independent of their degree of obesity.