SUMMARY The integrity of pituitary—adrenal function and growth hormone production was determined in 15 patients before and after treatment with diazepam (30 mg daily). There was no evidence of impairment; nor was the urinary excretion of catecholamines significantly altered. The reproducibility of the plasma corticosteroid response to insulin-induced hypoglycaemia was separately assessed and both the degree of fall in blood sugar and the rise in plasma corticosteroid level were found to be similar.