Sitagliptin + Metformin is a combination of two medicines: sitagliptin and metformin. Sitagliptin help your pancreas produce more insulin, facilitate effective use of insulin by the body, and reduce excess sugar that your liver makes. Metformin is a biguanide which lowers glucose production in the liver, delays glucose absorption from intestines and increases the body's sensitivity to insulin. Together, they provide better control of blood sugar.