According to WHO, the prevalence of diabetes mellitus is increasing dramatically year by year in the world. The current prevalence of diabetes in adults in China is about 9.7%, with a total of about 90 million, of which type 2 diabetes mellitus (T2DM) accounts for 90%. Diabetes mellitus usually coexists with obesity, and about 90% of people with T2DM are obese or overweight. The underlying mechanism of obesity in this disease is probably insulin resistance (IR). The release of inflammatory factors will lead to the migration and infiltration of macrophages into adipose tissue, producing more inflammatory factors, which will block the signaling pathway of insulin action, thus causing IR. More and more obese patients have undergone bariatric surgery and achieved good weight loss results. However, surprisingly, these bariatric surgeries have been effective in reducing the patient’s weight while also improving the coexisting disorders of glucose metabolism in most patients. Some obese patients with preoperative coexisting diabetes are in clinical remission or even complete clinical remission after undergoing surgery. There is even a growing body of research and evidence that these gastrointestinal surgical procedures are more effective in treating even normal weight diabetic patients. Principle: The main mechanisms of gastrointestinal surgery for the treatment of diabetes may be: (1) reduced food intake and absorption, thus reducing energy intake and glucose metabolic load; (2) lowering the patient’s body weight and reducing insulin resistance due to the fat accumulation of simple obesity; (3) altering the secretion of hormones in the intestine-insulin axis after gastrointestinal tract reconstruction, thus improving glucose metabolism. Surgery: Currently, there are three main types of bariatric surgery: food intake restriction, food absorption restriction and a mixture of both. Food intake restriction is based on reducing the size of the stomach to increase the feeling of fullness, thus reducing food intake. Food absorption restriction surgery is based on altering the gastrointestinal pathway so that the food bypasses part of the small intestine and is not fully absorbed. The representative procedure for both types is gastric bypass, which is currently the main procedure for the treatment of type 2 diabetes, with an efficiency of 80% to 85%, and the treatment effect is expected to be maintained for a long time. Gastric bypass surgery technique: The volume of gastric bursa should be as small as possible, and according to the literature, it is best to limit it to about 12ml to 25ml. The gastric bursa should be completely separated from the distal side of the stomach or at least separated by a straight cutting anastomosis with four rows of staples. The entire duodenum is left open as well as at least 40 cm above the proximal jejunum. The anastomosis of the gastric bursa to the Roux arm of the jejunum can be either anterior or posterior to the colon. The diameter of the anastomosis is between 0.75 cm and 1.25 cm. The length of the Roux arm is generally limited to between 75 cm and 150 cm, which can be adjusted according to the patient’s weight. Indications: All type 2 diabetic patients with poor results or intolerance after long-term non-surgical treatment can be considered for gastrointestinal surgery as long as there are no obvious contraindications to surgery. Better treatment results can be expected when patients meet the following conditions: (1) the patient’s age is ≤ 65 years; (2) the patient’s duration of T2DM is ≤ 15 years; (3) the patient’s islet reserve function is above 1/2 of the lower limit of normal and C-peptide is ≥ 2. At the same time, the patient has no serious mental disorder or intellectual disability; the patient fully understands the surgical modalities for treating diabetes, understands and is willing to assume the potential Patients understand the risks of complications, the importance of postoperative diet and lifestyle changes and are willing to tolerate them; patients can actively cooperate with postoperative follow-up, etc. are also factors to be considered in the selection of surgery. Complications: The perioperative mortality rate is about 0.5%, and the incidence of surgical complications such as anastomotic leak, bleeding, incisional infection, and pulmonary embolism is about 5%. Distant complications may include tipping syndrome, anastomotic stenosis, marginal ulceration, closure line dehiscence, and internal hernia. Lifelong Vit B12 supplementation is required, as well as iron, Vit B complex, folic acid, and calcium as needed. Our laparoscopic surgery department was early to perform various types of laparoscopic surgery and has now successfully performed gastric bypass surgery to treat type 2 diabetes.