Plasma-arginine-vasopressin response to insulin-induced hypoglycaemia.

Insulin-induced hypoglycaemia caused a threefold rise in plasma-arginine-vasopressin concentration (to 4-36 +/- 0-77 pmol/1) in ten subjects who had normal posterior-pituitary function. Plasma-arginine vasopressin reached a peak 30 min after injection of insulin. Plasma concentrations of arginine vasopressin obtained with hypoglycaemia were similar to those achieved after overnight dehydration for 14-16 h. No rise in plasma-arginine-vasopressin was observed in three patients with cranial diabetes insipidus in whom severe hypoglycaemia developed after insulin infusion. It is suggested that the measurement of arginine vasopressin during insulin-induced hypoglycaemia may be a useful clinical test of posterior-pituitary function.