The effect of rosiglitazone on retinol binding protein 4 in subjects of impaired glucose tolerance

Retinol-binding protein-4 (RBP4) is a novel adipokine, which is reported to be associated with obesity and insulin resistance (IR). We studied the effect of rosiglitazone (ROS), an insulin sensitizer, on the RBP4 plasma concentrations in subjects with impaired glucose tolerance (IGT). A single-blind, placebo-controlled comparison trial was conducted. A total of 26 IGT patients (mean age of 54 years) were enrolled; 14 received ROS (4 mg daily) and 12 received placebo. An enzyme immunoassay (EIA) was used to measure plasma RBP4 concentrations before and after therapy in both treatment groups. Plasma RBP4 concentrations were not associated with IR and cardiovascular risk factors with the exception of serum creatine levels. ROS therapy decreased RBP4 levels independent of IR, but associated with the changes in aspartate aminotransferase and triglyceride levels as well as basal serum RBB4 concentrations. In brief, plasma RBP4 concentrations in IGT subjects did not correlate with most cardiovascular risk factors and IR. However, treating IGT subjects with ROS resulted in decreased RBP4 levels independent of IR.