A 32-year-old woman who had been diabetic for 24 years presented with frequent, oligosymptomatic episodes of hypoglycaemia. Investigations showed that she had attenuated adrenocortical and pancreatic A-cell response to hypoglycaemia. Her plasma ACTH response to hypoglycaemia was also impaired but there was normal adrenocortical response to the injection of synthetic ACTH. Plasma glucagon response to intravenous arginine was also normal.
It is concluded that the blunted plasma cortisol response to insulin-induced hypoglycaemia in some long-standing diabetics is due to a pituitary or higher dysfunction, rather than adrenocortical dysfunction.