[Abnormalities of 24 hour (Holter) ECG monitoring in diabetics: involvement of cardiac autonomic neuropathy and/or insulin therapy].

In order to detect evidence of cardiac autonomic neuropathy, 24-hour continuous electrocardiographic monitoring was carried out on fifty-one diabetic patients (thirty-one IDD, twenty NIDD) and twenty-two healthy controls taking no treatment which could alter the heart rate. In the diabetic patients the minimum 24-hour heart-rate and the mean sleeping heart rate were significantly higher, and the maximum 24-hour heart rate and the ratio [(maximum-minimum heart rates)/minimum heart rate] were significantly lower. Evidence in one diabetic of cardiac autonomic neuropathy was found only as the difference (maximum-minimum heart rates). This index was found to be below 38/min (mean-2 SD of the controls) in seven diabetics, but only one of the nine diabetics with signs of autonomic neuropathy had this abnormal index. The mean values for the minimum and the mean sleeping heart rates were high in the IDD with or without signs of peripheral neuropathy and without signs of autonomic neuropathy but were not high in IDD with signs of autonomic neuropathy. These findings suggest the presence of cardiac autonomic neuropathy in diabetics. However, the possibility of insulin-induced tachycardia should be considered this tachycardia is probably related to stimulation of the sympathetic nervous system, which would explain the absence of abnormalities in IDD with autonomic neuropathy.