ACTH stimulation is the standard test for assessment of adrenal function. It was suggested that the low dose (1 microg) would be more sensitive for detecting mild secondary adrenal insufficiency than the usual dose of 250 microg. The aim of this study was to find the optimal diagnostic criteria and to compare standard dose test (SDT) with the low dose test (LDT). A group of patients treated with corticosteroids for the 6 months was considered to have hypothalamo-pituitary-adrenal impairment. Studies were performed in 14 corticosteroid-treated and 28 control subjects in random order on 2 consecutive days. Tests were analyzed using the receiver operating characteristic curve method. The best test was cortisol increment at 15 min of the LDT. It was significantly better than the cortisol concentration at 15 min of the SDT, the best test during the SDT (receiver operating characteristic curve area and 95% confidence interval: LDT, 0.997 and 0.956-0.999; SDT, 0.827 and 0.662-0.929; P = 0.0113). For the cortisol increment at 15 min of the LDT at 100% sensitivity, the diagnostic value was 100 mmol/L, and the specificity was 96%. Therefore, the LDT is superior to the standard dose test in the assessment of secondary adrenal insufficiency.

Objective: The aim of the study was to determine whether derangements in insulin pulsatility are related to the presence of insulin resistance or whether these changes occur only in non-insulindependent diabetes mellitus (NIDDM). Design and methods:The study included 26 obese, 11 NIDDM and 10 control subjects. The obese group was divided into a low insulin (plasma insulin <20 mU/l, OLI, 14 subjects) and a high insulin (OHI, 12 subjects) group. For pulsatility analysis blood was sampled every 2 min for 90 min. Pulsatility analysis was carried out using the PulsDetekt program. The insulin secretion randomness was quantified using interpulse interval deviation (IpID) and approximate entropy (ApEn). Conclusions: Decrease in insulin sensitivity was correlated with the reduction of insulin secretion regularity. Therefore irregular insulin secretion is related to a reduction in insulin sensitivity, and it is not unique to NIDDM.

It is well known that glucocorticoids induce insulin resistance, but the exact time scale in humans is not well known. The aim of the study was to determine the time scale of effects of pharmacologic doses of glucocorticoids on insulin sensitivity. Subjects were treated with repeated methylprednisolone infusions and oral prednisone for Graves' orbitopathy. Insulin sensitivity was determined using euglycemic hyperinsulinemic clamp (EHGC) before, during the first glucocorticoid infusion and after 2 months of treatment. EHGC started 2 h after the start of the glucocorticoid infusion, and lasted for 2 h. In another group of patients, insulin sensitivity was determined by short insulin tolerance test (SITT) before and during the first glucocorticoid infusion. SITT started 15 min after the start of the glucocorticoid infusion and lasted for 15 min. Ten subjects were included in each protocol. All were euthyroid during the study period. Four hours after the start of the glucocorticoid infusion significant reduction of insulin sensitivity was observed, which did not change for a further 2 months of glucocorticoid treatment [before 7.82 (95% confidence interval (CI) 5.35-10.29), first infusion, 4.93 (95% CI 2.99-6.87), after 2 months 5.36 (95%CI 3.91-6.81) mg/kg/min]. No significant change in insulin sensitivity occurred during the first 30 min of glucocorticoid infusion [before 139.7 (95%CI 94.1-185.3), during 146.7 (95%CI 106.3-187.1) mumol/l/min]. In humans, glucocorticoid- induced insulin resistance develops quickly, in about 4 h, and does not change during further glucocorticoid treatment.

Prolonged psychological stress is associated with a transient suppression of the HPA axis, manifested by low morning cortisol and reduced cortisol response to ACTH. The reduction of cortisol response is sufficient to cause false diagnosis of HPA insufficiency.