Sitagliptin is an oral medicine for diabetes. It is marketed as salt of phosphate under various brand names. It is a very effective medicine to control diabetes by controlling the sugar level. It is mostly recommended for type 2 diabetes mellitus alone or in combination with other medicines that cure diabetes. It is not recommended to treat type-1 diabetes. This drug is either sold alone or in combination with metformin or Thiazolidinediones (other anti-hyperglycemic agents).