OBJECTIVE: The Exenatide BID Observational Study (ExOS) was designed to evaluate the clinical effectiveness of exenatide BID use in patients with type 2 diabetes (T2D) in a real-world clinical practice setting in the United States. METHODS: Patients were enrolled from 74 practice sites from 9/2007 through 1/2009 and followed for 12 months. The primary effectiveness endpoint was achieving or maintaining hemoglobin A1C of