BACKGROUND Gastric cancer remains a significant global health concern. Radical gastrectomy is the primary curative treatment. Diabetes mellitus is a common comorbidity in patients undergoing surgery for gastric cancer, including radical gastrectomy. Previous studies have suggested that diabetes can negatively affect postoperative outcomes, such as wound healing, infection rates, and overall recovery. However, the specific impact of diabetes on recovery after radical gastrectomy for gastric cancer remains poorly understood. evaluate the influence of diabetes on postoperative recovery, including hospital stay duration, complications, and readmission rates, in patients undergoing gastrectomy for gastric cancer. Understanding these effects could help optimize perioperative management and improve patient outcomes. AIM To investigate the impact of diabetes on recovery after radical gastrectomy for gastric cancer and associated postoperative outcomes. METHODS This retrospective cohort study was performed at the Endocrinology Department of Xuanwu Hospital, Capital Medical University, Beijing, China. We examined patients who underwent radical gastrectomy for cancer between January 2010 and December 2020. The patients were divided into the diabetes and non-diabetes groups. The main outcomes included length of hospital stay, postoperative complications, and 30-day readmission rate. Secondary outcomes included quality of life indicators. Propensity score matching was used to adjust for potential confounding factors. RESULTS A total of 1210 patients were included in the study, with 302 diabetic patients and 908 non-diabetic patients. After propensity score matching, 280 patients were included in each group. Diabetic patients demonstrated significantly longer hospital stays (mean difference 2.3 days, 95%CI: 1.7-2.9, P < 0.001) and higher rates of postoperative complications (OR 1.68, 95%CI: 1.32-2.14, P < 0.001). The 30-day readmission rate was also higher in the diabetic group as compared to the non-diabetic group (12.5% vs 7.8%, P = 0.02). CONCLUSION Patients with diabetes mellitus undergoing radical gastrectomy for gastric cancer experience prolonged hospital stay, increased postoperative complications, and higher readmission rates, thus requiring optimized perioperative management strategies.