This is a placebo-controlled, randomized, double-blind, parallel arm, multicenter, dose-ranging phase IIb trial to assess glycemic and weight loss efficacy and safety of BMS-646256 in overweight and obese patients with type 2 diabetes who have been treated with diet and exercise only or with half-maximal or greater metformin (≥1500mg/day) or sulfonylurea monotherapy (stable dose for at least three months), but who remained inadequately controlled (HbA1c >7% and HbA1c<10%).