Evaluation of Glucose Lowering Effect, Safety and Tolerability of CS-917

Inclusion Criteria: * Drug naive or newly diagnosed type 2 diabetic subjects: * Never received oral antihyperglycemic or insulin therapy or * No oral antihyperglycemic or insulin therapy for more than 6 months since original diagnosis and * No insulin therapy within one year of screening, with the exception of use during hospitalization or for use in gestational diabetes and * No antihyperglycemic therapy for more than three consecutive days, or a total of of seven non-consecutive days, during the 8 weeks prior to screening. * HbA1C\>6.7% and \< or = to 10% at screening Exclusion Criteria: * Current insulin therapy * Symptoms of poorly controlled diabetes * History of diabetic ketoacidosis or hyperosmolar, nonketonic coma within one year of screening * Serum bicarbonate \< or = to 19 meq/L * Serum creatinine (Scr) \> 1.4 mg/dL (females) or 1.5 mg/dL (males) * Contraindication to metformin