Rosiglitazone improves insulin sensitivity and glucose tolerance in subjects with impaired glucose tolerance

Summary Objective  This study was designed to evaluate the effects of rosiglitazone (ROS) on insulin sensitivity, β-cell function, and glycaemic response to glucose challenge and meal in subjects with impaired glucose tolerance (IGT). Methods  Thirty patients with IGT (ages between 30 and 75 years and BMI (body mass index) ≤ 27 kg/m2) were randomly assigned to receive either placebo (n = 15) or ROS (4 mg/day) (n = 15). All participants underwent a 75-g oral glucose tolerance test (OGTT), meal test, and frequently sampled intravenous glucose tolerance test (FSIGT) before and after the 12-week treatment. Results  After 12 weeks of ROS treatment, there were significant increases in total cholesterol (TC) (4·25 ± 0·22 vs 4·80 ± 0·17 mmol/l, P < 0·001), high-density lipoprotein cholesterol (HDL-C) (1·25 ± 0·07 vs 1·43 ± 0·06 mmol/l, P < 0·05), and low-density lipoprotein cholesterol (LDL-C) (2·70 ± 0·15 vs 3·37 ± 0·17 mmol/l, P < 0·05) without changes in triglyceride concentration, TC/HDL-C and LDL-C/HDL-C ratio. Although the acute insulin response (AIR) to intravenous glucose and disposition index (measured as the ability of pancreatic β-cell compensation in the presence of insulin resistance) remained unchanged, the insulin sensitivity (SI) and glucose effectiveness (SG) were remarkably elevated (0·38 ± 0·06 vs 0·54 ± 0·09 × 10−5 min−1/pmol, P < 0·05; 0·017 ± 0·002 vs 0·021 ± 0·001 min−1, P < 0·05, respectively) in the ROS group. The glucose, insulin, and c-peptide areas under curve (AUC) in response to OGTT and the glucose and insulin AUC during meal were significantly ameliorated in the ROS group. Five out of 15 (33%) and two out of 15 (13%) subjects treated with ROS and placebo, respectively, reversed to normal response during OGTT (P < 0·05). Conclusion  Rosiglitazone treatment significantly improved insulin resistance and reduced postchallenge glucose and insulin concentrations in patients with impaired glucose tolerance without remarkable effects on β-cell secretory function.