Obesity is an important cause of diabetes because excess fat can lead to a rise in insulin resistance, making insulin less able to regulate blood sugar, requiring more insulin to control blood sugar, and the pancreas will slowly fail due to long-term overload, eventually causing diabetes. Many clinical cases prove that weight loss has a very great effect on the treatment of diabetes, sometimes even better than medication. However, weight loss is a long-term process, during the weight loss period, patients still have to take drugs and other ways to control blood sugar and slow down the development of the disease, and many hypoglycemic drugs tend to cause patients to become more fat, so more and more doctors began to recommend those patients who are obese more serious to treat diabetes through weight loss metabolic surgery. But after a lot of clinical studies and follow-up investigations, it was found that this type of surgery not only allows patients to maintain a more ideal weight in the long term, but also allows those patients with diabetes to control their blood sugar in the ideal range without using glucose-lowering drugs, and it is also effective in the long term, so later on, weight loss metabolic surgery became one of the standard treatment options for diabetes. One of the standard treatment options for diabetes, but due to its surgical nature, it is still only available for obese type 2 diabetic patients. Although the principle of weight loss metabolic surgery for diabetes is not completely clear now, according to existing studies, the main principles of this type of surgery for diabetes include: the surgery allows the patient to significantly reduce body weight and lower insulin resistance, the surgery restricts the patient’s diet and absorption and inhibits the patient’s postprandial blood glucose rise, and the surgery changes the hormone secretion of the patient’s gastrointestinal tract and the intestinal flora division, which directly reduces blood glucose and insulin resistance. The mechanism of weight loss metabolic surgery for diabetes is still under further study and may be applicable to more types of diabetic patients in the future.