To evaluate the therapeutic effect of Roux-en-Y anastomosis following subtotal gastrectomy on type 2 diabetes mellitus (T2DM) in non-obese patients.We performed a retrospective analysis of 16 non-obese patients with T2DM undergoing Roux-en-Y anastomosis following subtotal gastrectomy for stomach cancer and upper gastrointestinal tract ulcer.All the patients were followed up for 6 months after the surgery. Roux-en-Y gastrojejunostomy significantly lowered the levels of fasting plasma glucose (FPG), 2 h postprandial plasma glucose (2hPG), and glycated hemoglobin (HbA1c)(P0.05). Of these patients, 8 (50%) achieved adequate glycemic control without antidiabetic medication and 5 (31.25%) showed obvious improvement. The total effectiveness rate of the surgery was 81.25%.Roux-en-Y gastrectomy can effectively ameliorate the diabetic symptoms and might serve as a new treatment option for T2DM in non-obese patients.