BACKGROUND: The efficacy of various bariatric surgeries varies in reducing blood glucose levels. Given the distinct mechanisms and anatomical alterations associated with each procedure, it is crucial to compare their glycemic control outcomes. We hypothesize that proximal small intestinal bypass (PSIB) is superior in blood glucose reduction over Roux-en-Y gastric bypass (RYGB) and jejunoileal bypass (JIB). AIM: To compare the effectiveness of PSIB, RYGB, and JIB in lowering blood glucose. METHODS: Rats with streptozotocin-induced diabetes were randomly divided into PSIB, RYGB, JIB, and sham-operated groups. Body weight, food intake, fasting blood glucose level, oral glucose tolerance test, insulin tolerance test, liver enzymes, and blood lipids were measured. RESULTS: Postoperatively, only the JIB group had a lower body weight compared to the sham group. The food intake of the rats in all three surgical groups was significantly less than that in the sham group. Fasting blood glucose was reduced in all surgical groups and was lower in the PSIB group than in the RYGB and JIB groups. Glucose tolerance and insulin sensitivity improved in all three surgical groups compared to the sham group, but the improvement appeared earliest in the PSIB group. At six weeks post-surgery, the PSIB group showed a reduction in alanine transaminase levels and maintained a normal lipid profile. CONCLUSION: PSIB demonstrated excellent hypoglycemic effects in the early postoperative period, and had better efficacy than RYGB and JIB.