The effects of pioglitazone and metformin on plasma visfatin levels in patients with treatment naive type 2 diabetes mellitus

Aims: Circulating visfatin levels are altered in insulin resistant states. We evaluated the effects of two insulin-sensitizing hypoglycemic agents on plasma visfatin and adiponectin levels in patients with newly diagnosed and untreated type 2 diabetes mellitus (T2DM). Methods: Forty-four patients with T2DM were randomized to treatment either with pioglitazone (15-45 mg/day) or metformin (1000-2000 mg/day). Plasma visfatin and adiponectin levels and homeostasis model assessment of insulin resistance (HOMA-IR) scores were determined at baseline and at 12th week of treatment. Results: By the end of the 12th week, fasting plasma glucose, HbA1c, HOMA-IR scores and waist circumferences improved equally in both treatment arms. HDL cholesterol and adiponectin levels increased only in the pioglitazone group (p = 0.01 and p = 0.002., respectively). On the other hand, metformin treatment had additional regulatory effects on BMI, blood pressure and total and LDL-cholesterol levels (p = 0.002, p = 0.01, p = 0.004, p = 0.001 and p < 0.001, respectively). Neither pioglitazone nor metformin displayed a significant effect on circulating visfatin concentration. Conclusions: Despite improvements in insulin sensitivity and glycemic regulation, either pioglitazone or metformin treatment did not result in any effect on blood visfatin levels in patients with treatment naive T2DM. (C) 2008 Elsevier Ireland Ltd. All rights reserved.