Isfahan University of Medical Sciences, Isfahan, Iran


Background- Cardiovascular complications are the most common cause of mortality and morbidity in non-insulin dependent diabetes mellitus (NIDDM). Autonomic neuropathy is one of the complications of NIDDM, which may also involve the cardiovascular system. Autonomic system abnormality may increase the QTc interval. On the other hand, patients with prolonged QTc interval are prone to ventricular arrhythmia, especially unique torsade-de-points and also sudden cardiac death. This study intends to detect the prevalence of QTc prolongation in diabetic and non-diabetic patients as well as its correlation with diabetic autonomic neuropathy.
Methods and Results- This study includes 200 diabetic (case) and 200 non-diabetic patients (control group) with comparable age and gender. Evaluation of autonomic nervous system was carried out in all cases with prolonged QTc interval as well as in the control group.  The results of study in the case and the control group were compared.
The prevalence of prolonged QTc interval was significantly higher in the case group in comparison with the control group, 8% vs. 2%, respectively (p value = 0.012, OR = 4.3). Sympathetic nervous system evaluation in cases with QTc interval prolongation and negative exercise test demonstrated abnormal results in more than 50% of the case group (OR = 3). Parasympathetic nervous system evaluation test in the case group showed abnormal results in comparison to the control group (OR = 9).
Abnormality of the parasympathetic nervous system was three times more common than abnormality in the sympathetic nervous system.
Conclusions- With regard to the prolonged QTc interval in the case group in comparison with the control group and abnormal autonomic nervous system function in more than half of the case group, the probability of ventricular arrhythmia, torsade de points, is increased. The mentioned group is at increased risk of sudden cardiac death. Rendering approaches for decreasing the risk of sudden cardiac death in diabetic patients is seriously recommended