Onglyza (saxagliptin) is a prescription oral medication that treats diabetes mellitus. Onglyza has the saxagliptin hydrochloride. Together with exercise and diet, it reduces the levels of blood sugar in patients (adults) suffering from type 2 diabetes. It acts by regulating insulin levels produced by your body after eating. It can be used together with other medications for diabetes, but it does not treat type 1 diabetes.