The present invention relates to a novel modified release pharmaceutical composition of DPP-IV inhibitors or pharmaceutically acceptable salt thereof. In particular the present invention relates to a novel modified release composition of DPP-IV inhibitors or pharmaceutically acceptable salt thereof that achieves desired minimum effective plasma concentration of the DPP-IV inhibitor sufficient for effective glycemic control in subjects 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 DPP-IV inhibitors is also provided by the present invention.