Pioglitazone Compared with Metformin Increases Pericardial Fat Volume in Patients with Type 2 Diabetes Mellitus

Context: Peroxisome proliferator-activated receptor-gamma agonists are involved in fat cell differentiation. Objective: The objective of the study was to investigate the effect of pioglitazone vs. metformin on pericardial fat volume in type 2 diabetic (T2DM) patients. Furthermore, we aimed to assess the relationship between pericardial fat volume, other fat compartments, and myocardial function at baseline and after treatment. Design: This was a prospective, randomized, double-blind, intervention study. Setting: The study was conducted at a university hospital. Patients: Patients included 78 men with T2DM (aged 56.5 +/- 0.6 yr; glycosylated hemoglobin 7.1 +/- 0.1%) without structural heart disease. Intervention: Patients were randomly assigned to pioglitazone (30 mg/d) or metformin (2000 mg/d) and matching placebo during 24 wk. Main Outcome Measures: Pericardial and abdominal fat volumes and myocardial left ventricular function were measured by magnetic resonance imaging and hepatic and myocardial triglyceride content by proton magnetic resonance spectroscopy. Results: Pioglitazone increased pericardial fat volume [30.5 +/- 1.7 ml (baseline) vs. 33.1 +/- 1.8 ml], whereas metformin did not affect pericardial fat volume (29.2 +/- 1.5 ml vs. 29.6 +/- 1.6 ml, between groups P = 0.02). After correction for body mass index and age, only visceral fat volume correlated with pericardial fat volume at baseline (r = 0.55, P < 0.001). The increase in pericardial fat volume induced by pioglitazone was not associated with a decrease in left ventricular diastolic function. Conclusion: In T2DM patients, pioglitazone increases pericardial fat volume. This increase in pericardial fat volume did not negatively affect myocardial function after 24 wk. These observations question the notion of an inverse causal relationship between pericardial fat volume and myocardial function. (J Clin Endocrinol Metab 95: 456-460, 2010)