Evaluation of cardiovascular autonomic nervous functions in diabetics: Study in a rural teaching hospital

Introduction: Cardiovascular autonomic neuropathy (CAN) is a least understood complication of diabetes which is often underdiagnosed. It causes resting tachycardia, orthostatic hypotension, and exercise intolerance and is associated with higher cardiovascular mortality in diabetic patients. This stresses the need of early diagnosis of CAN to prevent higher mortality rates. Materials and Methods: Fifty cases of diabetes mellitus with no clinical evidence of cardiac disease were subjected to cardiac autonomic function (CAF) tests according to Ewing's criteria which included heart rate (HR) variability during deep breathing, Valsalva maneuver ratio, HR response on standing, blood pressure (BP) response to standing, and BP response to sustained handgrip to find the prevalence of CAN. Results: In this study, among 100 patients (50 case and 50 control), we found CAN in 52%. Out of which, parasympathetic neuropathy was seen in 52% of cases, and sympathetic neuropathy was seen in 26% of cases. CAF tests of HR variability during deep breathing, Valsalva maneuver ratio, HR response to standing, BP response to standing, and BP response to sustained handgrip found abnormal response in 68%, 40%, 52%, 12%, and 14%, respectively. Diabetic retinopathy and nephropathy were significantly associated with CAN (P = 0.0001, S). Conclusion: Prevalence of CAN among diabetics was 52%, and parasympathetic CAF tests are more sensitive for the detection of CAN than sympathetic CAF tests. Development of CAN in diabetic patients may lead to increased morbidity; thence, they should be routinely evaluated for CAN using these bedside tests.