BackgroundRoux-en-Y gastric bypass (RYGB) is an effective treatment for patients with type 2 diabetes mellitus (T2D) with obesity. However, T2D remission after surgery has not been adequately studied in Chinese patients with different obesity classes. The purpose of this study is to evaluate the medium-term metabolic results of RYGB in T2D patients with body mass index (BMI) >25 kg/m2 compared by obesity class.