Hypothalamic-pituitary-adrenal response to different tests in type 1 diabetes mellitus

OBJECTIVE: To determine whether different tests of the adrenocorticotropic hormone (ACTH) reserve are influenced by diabetic state and metabolic control in newly diagnosed type 1 diabetic patients. DESIGN AND METHODS: We evaluated the ACTH reserve in 10 patients with uncomplicated type 1 diabetes during periods of poor and improved metabolic control and in 10 healthy subjects. The ACTH-cortisol secretion was assessed by a diurnal profile, an intravenous corticotropin-releasing hormone (CRH) test and an insulin tolerance test (ITT). RESULTS: The diurnal profiles were similar in all groups. CRH resulted in a diminished ACTH response during poor compared with improved metabolic control (mean+/-SD) (AUC 4950+/-4227 vs. 5847+/-3788 ng/L min, p<0.05). The response in the diabetic patients during improved metabolic control was of the same magnitude as in the control subjects (5934+/-1778 ng/L x min). ITT elicited a similar ACTH and cortisol response in the diabetic patients during poor and improved metabolic control as in the healthy control subjects. CONCLUSIONS: The ITT was uninfluenced by diabetic state and metabolic control and should therefore be considered the method of choice in evaluation of the ACTH reserve in patients with type 1 diabetes.