Development of isolated ACTH deficiency in a man with type I diabetes mellitus

A 45-year-old man with type I diabetes mellitus of 25-yr duration and well controlled by conventional insulin therapy developed an isolated adrenocorticotropic hormone (ACTH) deficiency. He presented with a 3-month history of weight loss, weakness, anorexia and persistent tendency to hypoglycemia that he had never experienced before. Basal and dynamic endocrine testing disclosed absent cortisol secretion caused by an isolated ACTH deficiency due to a primary pituitary defect. Corticosteroid replacement therapy allowed again a good glycometabolic control. The possible causes of hypoglycemia in insulin-treated diabetes and the pathogenetic basis of the reported association are discussed.