Background Metabolic syndrome (MS), a constellation of metabolic abnormalities, has an intertwined link with morbid obesity and type 2 diabetes (T2DM).Gastric bypass (GBP) is considered an effective option for the management of these patients.However, most of the diabetes patients in China have distinguishing abdominal obesity rather than severe obesity, while some patients may have MS and some may not.Otherwise, data concerning non-morbid obesity patients with MS has rarely been reported.It is important to investigate if the same principles of GBP that improve diabetes with MS could be applied to the diabetes without MS in non-obesity patients.