Janumet (Sitagliptin / Metformin Hydrochloride) is used to control blood glucose (sugar) levels in adults with type 2 diabetes. It is used together with diet and exercise in patients whose blood glucose levels are not satisfactorily controlled with metformin (a diabetes medicine) used on its own, in patients who are already taking a combination of sitagliptin and metformin as separate tablets or in combination with a sulphonylurea, a PPAR-gamma agonist such as a thiazolidinedione, or insulin (other types of diabetes medicines) in patients whose blood glucose levels are not satisfactorily controlled with either of these medicines and metformin.