OBJECTIVE	To assess efficacy and safety of sitagliptin , a dipeptidyl peptidase-4 inhibitor , in combination therapy with metformin ( 1500 mg/day ) and pioglitazone ( 30 mg/day ) in patients with type 2 diabetes ( T2DM ) with inadequate glycemic control ( hemoglobin A1c [ HbA1c ] 7.5 % and 11 % ) .\