- Type 2 Diabetes Mellitus and on stable dose of Metformin. Patients must have been on a stable dose of oral metformin (at least 1000 mg/day) for a minimum of 3 months prior to screening evaluation and will be required to continue their stable dose of metformin throughout the study. Patients on a stable dose of metformin plus a sulfonylurea (SU) or metformin plus a dipeptidyl peptidase-IV (DPPIV) inhibitor for a minimum of 3 months prior to Screening evaluation may be allowed