The present invention relates to a novel modified release pharmaceutical composition of sitagliptin or pharmaceutically acceptable salt thereof. In particular the present invention relates to a novel modified release composition of sitagliptin or pharmaceutically acceptable salt thereof that achieves desired minimum effective plasma concentration of the sitagliptin sufficient for effective glycemic control in patients with type 2 diabetes mellitus. A method of improving glycemic control in adults with type 2 diabetes mellitus and reducing or eliminating fluctuations in plasma concentration of sitagliptin is also provided by the present invention.
