Context: Thiazolidiones (TZD) improves insulin sensitivity in type 2 diabetes via effects on fat metabolism, whereas growth hormone (GH) stimulates lipolysis and induces insulin resistance.
Objective: To evaluate the effects of TZD on fat metabolism and insulin sensitivity in GH-treated GH deficient (GHD) patients.
Design: Randomized, placebo-controlled, double-blind parallel-group study including 20 GHD patients on continued GH replacement therapy. The patients were studied before and after 12 weeks.
Intervention: Patients received either tablet pioglitazone 30 mg (N=10) or placebo (N=10) once daily for 12 weeks.
Results: 12 weeks of pioglitazone treatment in GH-replaced GHD patients was associated with improved insulin sensitivity (P=0.03) and increased basal glucose oxidation (P=0.004). Change in insulin-stimulated adiponectin level after pioglitazone treatment was positive correlated to the change in insulin-stimulated total glucose disposal (R=0.69, P=0.04). Pioglitazone significantly decreased basal free fatty acid levels (P=0.02) and lipid oxidation (P=0.02). Adiponectin levels almost doubled during pioglitazone treatment (P=0.0001).
Conclusion: The impact of GH on lipolysis and insulin sensitivity is modified by administration of PPARγ agonists.