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 I diabetic patients. Design and methods: We evaluated the ACTH reserve in 10 patients with uncomplicated type I diabetes during periods of poor and improved metabolic control and in 10 healthy Subjects. The ACTH-cortisol secretion Aas 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 +/- 3788ng/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.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 I diabetes.