Type 2 Diabetes Mellitus is most common form of diabetes. Oral agents are the main stay of pharmacological treatment for type 2 diabetes mellitus. Dipeptidyl peptidase-4 (DPP-4) inhibitors represent a new therapeutic approach for type 2 diabetes. Sitagliptin is highly selective DPP-4 inhibitor that has been approved for type 2 diabetes therapy. It acts by increasing the levels of incretins by inhibiting their degradation by DPP-4. Sitagliptin has been shown to be effective, well tolerated and safe in the treatment of type 2 diabetes in monotherapy or in combination with metformin or thiozolidinediones with minimal side effects.