To compare the 1-year effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy with Roux-en-Y duodenal bypass (SG+RYDJB) on weight loss, remission of diabetes, and postoperative complications in patients with obesity and type 2 diabetes. A single-center retrospective cohort study was conducted at the First Affiliated Hospital of Nanjing Medical University from January 2020 to December 2020. Sixty-four patients with type 2 diabetes and body mass index (BMI) of 27.5-40.0 kg/m were included in this study and divided into the RYGB group (=34) and the SG+RYDJB group (=30). In both procedures, the biliopancreatic branch was measured 100 cm distal to the Treitz ligament, and the food branch was measured 100 cm distal to the gastric or duodenojejunal anastomosis. Patients were followed up by telephone or WeChat, a free messaging and calling app at 1, 3, 6, and 12 months postoperatively to determine their weight loss and remission of diabetes. The primary outcomes were the weight loss and reduction in blood glucose concentrations at 1 year after surgery and postoperative complications. Other postoperative changes, including body weight, BMI, percentage of total weight loss (%TWL), percentage of excess weight loss (%EWL), glycated hemoglobin A1c (HbA1c), and fasting blood glucose at 1 year after surgery were also assessed. There were no significant differences in baseline data between the two groups (all >0.05). No conversion to open surgery or death occurred in either group. Operation time was longer in the SG+RYDJB than the RYGB group (137.8±22.1 minutes vs. 80.0±24.9 minutes, =9.779, <0.001) and the incidence of perioperative complications was higher in the SG+RYDJB than the RYGB group (20% [6/30] vs. 2.9% [1/34], χ=4.761, =0.029). However, the postoperative hospital stay was similar between the two groups [3.0 (3.0, 4.3) days vs. 3.0 (4.0, 6.0) days, =641.500, =0.071]. Perioperative complications comprised small gastric pouch anastomotic leakage in one patient in the RYGB group and leakage (three patients) and bleeding (two patients with gastrointestinal bleeding and one with trocar site bleeding) in the SG+RYDJB group. Long-term complications were as follows. The incidence of anemia was significantly higher in the RYGB than the SG+RYDJB group (26.5% [9/34] vs. 3.3% [1/30], χ=6.472, =0.011). However, there were no significant differences in incidences of postoperative reflux, dumping syndrome, alopecia, diarrhea, constipation or foul-smelling flatus between the two groups (all >0.05). Compared with 1 year before surgery, the body weights and fasting plasma glucose concentrations of patients in the SG+RYDJB and RYGB group (72.4±10.6 kg vs. 98.5±14.2 kg, respectively; 68.2±10.0 kg vs. 91.9±14.8 kg, respectively), BMI (25.2±2.9 kg/m vs. 34.3±4.2 kg/m, respectively; 24.3±2.4 kg/m vs. 32.7±3.7 kg/m, respectively) (5.5±1.6 vs. 10.6±3.3, respectively; 5.8±2.1 vs. 9.0±3.4, respectively); HbA1c (5.7±0.8 vs. 9.7±1.2, respectively; 9.1±1.9 vs. 5.9±0.9, respectively) were significantly lower at 1 year after surgery (all <0.05). However, the % TWL (26.5%±6.0% vs. 25.6%±4.4%, =0.663, =0.510) and % EWL (109.1%±38.2% vs. 109.4%±40.3%, =-0.026, =0.026), rate of complete remission of diabetes at 1 year (80.0% [24/30] vs. 82.4% [28/34], χ=0.058, =0.810] did not differ significantly between the two groups (all >0.05). Although SG+RYDJB surgery compared with RYGB is more difficult to perform, it can achieve similar weight loss and remission of diabetes and is associated with a lower incidence of anemia because of the preservation of the pylorus.