【Abstract】〓Objective〓To observe the effects of Roux-en-Y gastric gastrointestinal reconstruction surgery on blood glucose and insulin resistance of patients with gastric carcinoma complicated by type 2 diabetes. Methods〓Thirty-one patients with gastric carcinoma complicated by type 2 diabetes who underwent radical gastrectomy and Roux-en-Y gastric gastrointestinal reconstruction were collected. The weight, body mass index (BMI), fasting blood glucose (FPG), fasting insulin (FINS), fasting C peptide (FCP), 2 hour postprandial blood glucose (2hPG), 2 hour postprandial insulin (2hINS), 2 hour postprandial C peptide (2hCP), glycosylated hemoglobin (HbA1c) and insulin resistance index (HOMA-IR) were detected, the index changes were estimated before operation and six months after the operation. Results〓Of 31 cases, 27 patients received insulins treatment, 2 patients with oral medication and 2 with simple diet and exercise therapy before operation, and 14 patients with insulin treatment, 6 with oral medication and 11 with simple diet and exercise therapy at six months after the operation. The difference was statistically significant betwee pre- and post-operation. (P<0.05). The weight, BMI, FPG, FINS, 2hPG, 2hINS, HbA1c and HOMA-IR in patients at six months after the operation were lower than those in patients before operation (P<0.05). The FCP and 2h CP levels in patients at six months after the operation were higher than patients before operation (P<0.05). Conclusion〓Roux-en-Y gastric gastrointestinal reconstruction can improve blood glucose and insulin resistance in patients with gastric carcinoma complicated by type 2 diabetes.