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.

Growth hormone response to the insulin tolerance and clonidine tests in type 1 diabetes.

The insulin tolerance test (ITT) is regarded the gold standard for assessing growth hormone (GH) release in adult patients with suspected GH deficiency. Some of these patients also have diabetes mellitus. There are contradictory reports regarding the GH response to ITT in type 1 diabetic patients with varying degrees of metabolic control. This is also true for the clonidine test. We studied ten patients with uncomplicated type 1 diabetes mellitus during periods of poor and improved metabolic control and compared them with ten healthy control subjects. The GH secretion was assessed by an ITT with an insulin infusion of 2.5 mU/kg/min and an intravenous clonidine test. The GH response to ITT was similar during poor and improved metabolic control (mean +/- SEM) (AUC 2327 +/- 616 vs. 2649 +/- 508 microg/l x min) and did not differ from the response in control subjects (AUC 2587 +/- 343 microg/1 x min). The clonidine test induced a significantly greater GH response during poor than during improved metabolic control in the diabetic patients (AUC 2598 +/- 492 vs. 1508 +/- 368 microg/l x min, p < 0.05); this response was greater than in the control subjects (670 +/- 226 x microg/l x min, p < 0.005 vs. improved metabolic control). Thus, the GH response to ITT is similar in diabetic patients with varying degrees of metabolic control and healthy subjects, while the GH response to the clonidine test is higher in the type 1 diabetic patients than in healthy controls.