There are indications for gastric diversion surgery for the treatment of diabetes mellitus, and it is reliable if the indications are met; it is unreliable if the indications are not met and the treatment is not effective. Indications for gastric diversion surgery: obesity-related type 2 diabetes mellitus, pancreatic islet function in the compensatory phase, no serious diabetic complications, and a history of diabetes less than 15 years or age less than 70 years. Gastric diversion surgery helps to control weight and alleviate diabetes. Contraindications to gastric diversion surgery, include fasting C-peptide levels less than one-third of normal, elderly people over 70 years of age, diabetes with a history of more than 15 years, advanced diabetes, inability to tolerate the surgery, and the presence of severe organic lesions or complications. Whether gastric diversion surgery can be performed to treat diabetes, it is recommended to consult the relevant doctor.