Abstract: Objective To explore the related factors affecting postoperative blood glucose level in patients with gastric cancer complicated with type 2 diabetes mellitus, and provide reference for better selection of digestive tract reconstruction and control of postoperative blood glucose level. Methods Retrospective analysis was made on the clinical data of 179 patients with gastric cancer complicated with type 2 diabetes mellitus admitted to Gastroenterological Oncology Surgery, Affiliated Hospital of Nanjing University of Traditional Chinese Medicine from January 2008 to December 2018. Single factor analysis was carried out on the clinical factors that might affect the postoperative blood glucose level by chi-square test, P<0.05 was considered as the relevant factor. Binary logistic regression analysis was performed on the related factors, P<0.05 was an independent factor. Results Radical resection of gastric cancer was performed in 179 patients, 4 of them were cured of diabetes after operation, 122 patients were relieved of diabetes after operation, and the effective rate of postoperative improvement of blood glucose level was 70.39%(126/179). Single factor analysis showed that the age, coronary heart disease or not, preoperative treatment of diabetes, whether to remove the whole stomach, biliopancreatic shunt loops present or absent, duration of diabetes and preoperative fasting c-peptide level were associated with postoperative blood glucose level. Binary Logistic regression analysis showed that biliopancreatic shunt loops present or absent, duration of diabetes and preoperative fasting c-peptide level were gastric cancer combined with type 2 diabetes independent influence factors of postoperative blood glucose levels. Conclusion Analysis results show that biliopancreatic shunt loops present or absent, duration of diabetes and preoperative fasting c-peptide level are gastric cancer combined with type 2 diabetes independent influence factors of postoperative blood glucose levels. For a shorter duration of diabetes, patients with normal preoperative fasting c-peptide levels roughly, digestive tract reconstruction by bile pancreatic diversion during surgery can better improve postoperative blood glucose levels.