Endocrine Abstracts

Background: Although it is well known that glucocorticosteroids induce insulin resistance, probably due to postreceptor defects, the exact time scale is still a matter of debate.

Objective: The aim of the present study was to determine the time scale of effects of therapeutic doses of glucocorticoids on insulin sensitivity.

Methods: Study group consisted of 20 patients with Graves ophtalmopathy who were treated with corticosteroids for the first time. Infusion consisted of 500 mg of methylprednisolon suspended in normal saline and infused at a constant rate for four hours. In group I (10 patients; 8 female, 2 male, 50±11 years, BMI 24.1±4.4 kg/m²) insulin sensitivity was determined using euglicemic-hyperinsulinemic clamp, before, during the first methylprednisolone infusion and after two months of glucocorticoid treatment. Insulin clamp started two hours after the beginning of methylprednisolone infusion, and lasted for two hours (until the end of corticosteroid infusion). In II group II (10 patients; 7 female, 3 male, 45±11 years, BMI 22.3±2.2 kg/m²) insulin sensitivity was determined by insulin tolerance test (ITT). ITT started 15 minutes after beginning of methylprednisolon. We calculated insulin sensitivity as a slope of glucose disappearance from 3 to 15 minutes.

Results: There were no significant differences in regard to age, gender and BMI between the two groups. Group I: Steady state insulin concentration was not significantly different between the observed period (161±56 vs. 141±49 vs. 156±33 mU/l, P=0.589). However, there was a significant reduction in the whole body glucose disposal rate four hours after the infusion beginning (P=0.001). Two months after the whole body glucose disposal rate was still significantly reduced compared to the period before glucocorticoids (P=0.012). Group II: Insulin sensitivity measured using ITT was not different between the first 30 min of the glucocorticoid infusion (P=0.622).

Conclusion: It is suggestive that glucocorticoids exert full effects on the insulin sensitivity during the first few hours of the treatment, but with no change in the first 30 minutes.