Sitagliptin, sold under the brand name Januvia among others, is an anti-diabetic medication used to treat type 2 diabetes. In the United Kingdom it is listed as less preferred than metformin or a sulfonylurea. It is taken by mouth. It is also available in the fixed-dose combination medication sitagliptin/metformin (Janumet, Janumet XR). Sitagliptin was developed by Merck & Co. and approved for medical use in the United States in 2006. In 2020, it was the 74th most commonly prescribed medication in the United States, with more than 9 million prescriptions.