The effects of pioglitazone and metformin on plasma visfatin levels in patients with treatment naive type 2 diabetes mellitus - Erdem, G; Dogru, T; Tasci, I; Bozoglu, E; Muhsiroglu, O; Tapan, S; Ercin, C N; Sonmez, A (Diabetes Res Clin Pract, 2008)