Because type 2 – diabetes is characterized by progressive pancreatic cell failure, we see in clinical practice that the condition of diabetic patients is progressively aggravated despite careful treatment by internal medicine. In addition, the treatment of diabetic patients requires that all 3 items of blood lipids, blood pressure and blood glucose should be attained, otherwise it has little significance to prevent complications of diabetes. However, according to statistics, it is quite a minority of people who achieve the 3 standards for diabetes. In 1981, when people performed bariatric surgery for obese patients, they accidentally found that some diabetic patients who underwent surgery had stable blood sugar for a long time after surgery and did not need to take any hypoglycemic drugs or apply insulin. After more than 30 years of clinical observation and research, it has been confirmed that surgical treatment of obese diabetes can achieve good results, and about 80% of patients can maintain long-term stability of blood sugar after surgery. At present, the American Diabetes Association, the International Diabetes Federation and the World Health Organization treatment guidelines all clearly point out that surgery should be the first choice for patients with obesity combined with diabetes, and the Chinese diabetes prevention and treatment guidelines also clearly point out that surgery has good effects for patients with obesity combined with diabetes. Currently, academics believe that the discovery of bariatric surgery for diabetes is of equal value to the discovery of insulin, and some scholars predict that the theory of diabetes may have to be rewritten. The mechanism of surgery for type 2 – diabetes is to reduce the excessive calorie intake and absorption, which results in weight loss, reduces the load on the pancreatic cells, relieves insulin resistance, and increases the intestinal secretion of hormones favorable to the pancreas and decreases unfavorable hormones due to the isolation of the upper 12 fingers and jejunum and intestinal rerouting.