No difference in glycosphingolipid metabolism and mitochondrial function in glucocorticoid-induced insulin resistance in healthy men

Objective: Glucocorticoids (GCs) are well known to induce insulin resistance; however, mechanisms that cause the impairement of the insulin signaling pathway have not yet been identified. In this study we measured whether GC-induced insulin resistance in humans is related to changes in muscle ceramide, GM3, and muscle mitochondrial function. Methods: In a randomized, placebo-controlled, double-blind, dose-response intervention study, 32 healthy males (aged 22 ± 3 years; body mass index 22.4 ± 1.7 kg/m(-2)) were allocated to prednisolone (PRED) 7.5 mg once daily (n = 12), PRED 30 mg once daily (n = 12), or placebo (n = 8) for 2 weeks using block randomization. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp before and after treatment. Muscle biopsies were performed to measure ceramide, monosialodihexosylganglioside (GM3), and mitochondrial function. Results: Peripheral insulin sensitivity was dose dependently decreased after the PRED treatment. Muscle ceramide and GM3 concentration and mitochondrial function were not altered by 2 weeks of PRED treatment. Conclusion: Short-term GC treatment dose dependently impaired whole-body insulin sensitivity in healthy males, without concomitant changes in muscle ceramide, GM3, or mitochondrial function. These findings suggest that other mechanisms play a role in GC-related impairment of insulin sensitivity