In addition to traditional medical treatment, bariatric surgery is also one of the standard options for the treatment of diabetes, and it is often more effective than traditional treatment, allowing patients to achieve a higher quality of life than with medical treatment. However, weight loss metabolic surgery has many limitations in the treatment of diabetes. So far, this treatment is only for obese type 2 diabetes, and it also requires that the patient’s pancreatic islets still have some insulin secretion, so surgery is not recommended for low weight diabetic patients, and the treatment effect is very limited. The limitations of surgical treatment of diabetes have a lot to do with its treatment mechanism. In the past, it was widely believed that weight loss metabolic surgery for diabetes was mainly attributed to the significant weight loss of patients after surgery, which reduced the insulin resistance produced by fat cells and enhanced the effect of insulin to control blood glucose. Therefore, weight has always been one of the basic requirements for surgical treatment of diabetes. However, with the increasing number of cases of surgical treatment of diabetes and in-depth research, it has been found that surgical treatment of diabetes does not depend entirely on weight loss, and some patients’ blood glucose is well controlled before they have lost much weight after surgery, and they even stop taking hypoglycemic drugs directly. It has been found that surgical treatment of diabetes is related to a variety of factors such as alteration of gastrointestinal hormone secretion, flora division, and restriction of food digestion and absorption, in addition to reduction of fat-induced insulin resistance. These findings also provide a theoretical basis for weight loss metabolic surgery to treat low weight type 2 diabetic patients, which is expected to allow more diabetic patients to be treated through surgery.