Comparative Study on Cardiovascular Autonomic Function Tests in Type 2 Diabetes Mellitus Patients with and without Diabetic Retinopathy

Autonomic dysfunction is common in diabetics and presence of cardiac autonomic neuropathy is responsible for sudden death in diabetics. Detecting subclinical Cardiac Autonomic Neuropathy (CAN) early is crucially important for treatment and for preventing potentially serious consequences of CAN.

The aim of the study is to clinically assess cardiovascular autonomic function tests in type 2 diabetes mellitus patients and compare those with healthy normal subjects.

The study included 60 type 2 diabetic patients including 30 patients without any retinopathy and 30 others with non-proliferative diabetic retinopathy(NPDR), and 60 control subjects matched for age and gender. Autonomic function tests as given by Ewing were performed on all subjects to assess the parasympathetic and sympathetic nervous activity. These tests include heart rate response to deep breathing, valsalsa ratio, 30: 15 ratio, and blood pressure response to standing and sustained hand grip. Statistical analysis of the data was done using One way ANOVA (Analysis of Variance) and multiple comparisons were done using post hoc Tukey Multiple Comparison Test. Statistical significance was set at 0.05.

The results of our study show that there is decrease in cardiovascular autonomic functions more in diabetic patients with NPDR as compared to diabetic patients without retinopathy.

We conclude that there is involvement of both cardiovasvascular sympathetic and parasympathetic nervous system in patients with type 2 diabetes mellitus. So, type 2 DM patients should be evaluated for presence of autonomic dysfunction as early as possible to prevent complications and to improve the prognosis of the disease.