Objective To observe the curative effect on non-obese type 2 diabetes and the effect on change of glucagon-like peptide-1 (GLP-1) of gastric bypass operation. Methods Thirty-two cases of gastric ulcer with non-obese type 2 diabetes were suffered gastric bypass operation. Plasma glucose concentrations, insulin and GLP-1 were measured respectively in fasting and postprandial conditions before operation and in week 1, 2, 3 and month 1, 3, 6 after gastric bypass operation, and the body mass index (BMI), homeostasis model assessment β cell function index (HBCI) and glycosylated hemoglobin (HbA1c， the index was detected only before operation and in month 3, 6 after operation) were also measured. The turnover of the diabetes condition in the 6th month after surgery was observed. Results Compared with the levels before operation, the fasting and postprandial plasma glucose levels were descending (P＜0.05), fasting and postprandial plasma insulin and GLP-1 levels were ascending (P＜0.05), HBCI was ascending and HbA1c was descending significantly after operation respectively (P＜0.05), while BMI changed un-significantly after operation (Pgt;0.05). The diabetes control rate was 78.1%(25/32) overall six months after operation. Level of GLP-1 was negatively correlated with level of plasma glucose (P＜0.05) and positively correlated with level of insulin (P＜0.05). Conclusions Gastric bypass operation can markedly reduce plasma glucose level on the type 2 diabetes patients with non-obese, and the hypoglycemic effect may be contributed by more GLP-1 secretion that caused more insulin secretion, which doesn’t depend on the loss of weight.