Autonomic dysfunction and severe hypoglycaemia in insulin dependent diabetes mellitus

The aims of the present study were to investigate the relationship between severe hypoglycaemia and autonomic dysfunction in diabetic children, and to assess the glycaemic response to an insulin infusion test. In a one year period, 12 of 69 diabetic patients (17%) experienced at least one severe episode of hypoglycaemia, defined as an event which required outside assistance. All patients underwent five cardiovascular autonomic tests. Seven of the hypoglycaemic patients showed three or more abnormal autonomic tests. Among the 57 non-hypoglycaemic diabetics, there was no patient with three or more abnormal tests. In hypoglycaemic diabetics with and without autonomic dysfunction, and in eight healthy age matched subjects an insulin infusion test was performed. A pronounced blood glucose decline and a subnormal increase in heart rate during insulin infusion were obtained in patients with autonomic dysfunction. Thus, severe hypoglycaemia may be due to impaired defence mechanisms against blood glucose decline in diabetic children with autonomic dysfunction.