Pharmacodynamic Effects of Low-Dose Pioglitazone in Patients with the Metabolic Syndrome without Diabetes Mellitus.

STUDY OBJECTIVE: To determine the effects of low-dose pioglitazone on plasma adipocyte-derived cytokines, high-sensitivity C-reactive protein (hs-CRP), and components of the metabolic syndrome in adults with the metabolic syndrome without diabetes mellitus.

DESIGN: Prospective, randomized, double-blind, placebo-controlled study.

SETTING: University of Colorado Clinical and Translational Research Center.

PATIENTS: Thirty-two men and women, aged 30-60 years, without diabetes who had a clinical diagnosis of the metabolic syndrome, as defined by the American Heart Association/National Heart, Lung, and Blood Institute criteria.

INTERVENTION: Patients were randomly assigned to receive oral pioglitazone 7.5 mg daily or matching placebo for 8 weeks.

MEASUREMENTS AND MAIN RESULTS: The primary end point was the change in plasma high-molecular-weight (HMW) adiponectin level from baseline to week 8. Other end points were changes in plasma total adiponectin, omentin, and hs-CRP levels, and changes in components of the metabolic syndrome (e.g., insulin sensitivity) from baseline to week 8. Pioglitazone was associated with a significant increase in plasma HMW adiponectin from baseline to week 8 compared with placebo (+47% vs -10%, p<0.001). Insulin sensitivity increased significantly from baseline to week 8 in the pioglitazone group (+88%, p=0.02) but not in the placebo group (+15%, p=0.14). Change in HMW adiponectin was significantly correlated with the change in insulin sensitivity in the pioglitazone group (r = 0.784, p=0.003). No significant differences in mean percentage changes in plasma total adiponectin, omentin, and hs-CRP levels were observed between the pioglitazone and placebo groups. Likewise, changes in body weight, insulin sensitivity, glucose, lipids, and blood pressure did not differ significantly between the groups.

CONCLUSION: Low-dose pioglitazone favorably modulates plasma HMW adiponectin, which was associated with an improvement in insulin sensitivity, in patients with the metabolic syndrome without diabetes.