SummaryDiabetic autonomic neuropathy is a poorly defi ned neurologic entity with morbid and occasional lethal consequences. Cardiovascular effects of the diabetic autonomic neuropathy may include resting tachycardia, postural hypotension and painless myocardial infarction. The involvement of cardiovascular reflexes (beat-to-beat variation during breathing of Valsalva manoeuvre) assesses a cardiac parasympathetic dysfunction.The occurrence of a postural hypotension implies an orthosympathetic damage. We analysed the incidence of autonomic neuropathy in a group of totally insulindependent diabetic patients (mean circadian C peptide level: 0.04 + 0.003 pmol/ml, mean±SEM) and in a group of diabetic patients, with a residual insulin secretion (mean circadian C peptide level: 0.80±0.09 pmol/ml). 44 % of all the patients had up to 4 cardiovascular abnormal tests.Postural hypotension was observed in 11 % of the subjects. We found a significative correlation between the autonomic neuropathy and the duration of diabetes in subjects of group I (p<0.01). No correlation between autonomic neuropathy and C peptide level or mean glycosylated hemoglobin was observed. The high incidence of autonomic neuropathy and the poor prognosis of this diabetic complication justifies its systematic research in all type I and type II diabetic patients.