The ECG based heart rate variability (HRV) measurements has become an important method of assessment of the cardiac autonomic regulation. There is a large body of clinical and experimental evidences indicating that reduced HRV is a predictor of death in patients after myocardial infarction and with heart failure. Diabetic autonomic neuropathy (DAN) is a serious and common complication of diabetes. Cardiovascular autonomic neuropathy (CAN) is the most studied and clinically important form of DAN. Published data demonstrate that CAN is strongly associated with an increased risk of myocardial ischaemia, serious arrhythmias, exercise intolerance and mortality. The determination of the presence of CAN is usually based on Ewing\'s tests. Measurement of HRV is readily available method and serves to establish diagnosis of autonomic dysfunction. The reduction in parameters of HRV seems not only to carry negative prognostic value in patients with diabetes but also to precede the clinical expression of autonomic neuropathy HRV evaluation in diabetes can encourage physician to improve further therapy.