The association between cardiac autonomic neuropathy and diabetes control

Introduction: Cardiac autonomic neuropathy (CAN) is one of major complications of diabetes mellitus (DM) that increases the risk of cardiovascular disorders, abnormal ventricular depolarization with poor prognosis as well as increased mortality and morbidity. Indeed, CAN has close relation with blood glucose level in diabetic patients. We investigated the relation of CAN with diabetes control. Materials and methods: Totally, 115 diabetic patients (mean age 50.87±13.90 years old; 78 females) underwent study. All patients had DM and cardiac sinus rhythm. Nobody had sickness affecting cardiac rhythm and blood pressure. In addition, they did not take drugs that had effect on blood pressure, cardiac rhythm, and QT interval. Forty-six patients had tight and 69 patients had uncontrolled DM according to American Diabetes Association (ADA) criteria. The CAN was assessed based on heart rate variation during physical examination (at rest tachycardia and orthostatic hypotension) and standard Ewing’s tests (deep-breathing and laying-to-standing tests) with bedside continuous ECG recording. The P-value <0.05 is considered significant. Results: Seventy-five patients (65.2%) had CAN. In patients with CAN, 13.9% were symptomatic and 51.3% were asymptomatic. Resting tachycardia and hypotension were found in 5.2%, 8.7% of patients, respectively. Abnormal deep-breathing and laying-to-standing tests were found in 73% and 71.3% of asymptomatic patients, respectively. CAN was more prevalence at uncontrolled DM (67.3% vs 63.7%) but the difference was not significant. The prevalence of CAN had direct association with duration of DM in both tight and uncontrolled groups (P<0.05). The mean of age, sex, and type of treatment had no association with CAN prevalence. Conclusion: The prevalence of CAN, especially asymptomatic type, was high. Its prevalence was increased with prolonged duration of DM. But we did not find any relationship between CAN and glycemic control level.