Rapid effect of single-dose rosiglitazone treatment on endothelial function in healthy men with normal glucose tolerance: data from a randomised, placebo-controlled, double-blind study.

Antidiabetic thiazolidinediones (TZDs) improve endothelial function in patients with or without type 2 diabetes. The present randomised, placebo-controlled, double-blind study examined the time course of a single dose of rosiglitazone on flow-mediated endothelium-dependent vasodilation (FMD), metabolic parameters, and its effect on inflammatory markers in non-diabetic men. Forty non-obese, healthy men with normal glucose tolerance were randomised to a single dose of rosiglitazone (8 mg) or placebo, and FMD was assessed at baseline as well as after 6 h and 24 h. Rosiglitazone did not significantly affect blood glucose and insulin levels or lipid parameters after 6 and 24 h compared with placebo. Treatment with rosiglitazone significantly increased FMD after 6 h from 4.3% (3.3; 4.9) to 7.6% (5.6; 9.2) (p<0.0001 vs. baseline) resulting in a highly significant effect compared with placebo (p<0.0001 for difference between groups). After 24 h FMD was still significantly higher in the rosiglitazone group compared with baseline (p=0.001), but the effect was no longer statistically significant versus placebo (p=0.171). Our study shows a very rapid effect of single dose rosiglitazone treatment on endothelial function in non-diabetic healthy men, underscoring the hypothesis that TZDs may exhibit direct effect in the vasculature independent of their metabolic action.