Bariatric surgery is an effective treatment for morbid obesity, and studies have shown that bariatric surgery in severely obese patients can lead to clinical remission in 60-80% of patients with type 2 diabetes, with better outcomes when the disease is in its early stages. With improved surgical safety and the implementation of minimally invasive surgery, the research evidence for gastrointestinal bariatric surgery for the treatment of patients with obesity-related type 2 diabetes is gradually improving. And it significantly reduces the complication rate of diabetes. The main types of bariatric surgery currently performed in clinical practice include Roux-en-Y gastric bypass (RYGB), laparoscopic adjustable gastric banding (LAGB), laparoscopic sleeve gastrectomy (LSG), and laparoscopic gastric bypass (LAGB). sleeve gastrectomy (LSG), and biliopancreatic Diversion-Duodenal switch (BPD/DS). Among them, gastrointestinal bypass surgery (RYGB) and laparoscopic gastric banding (LAGB) are the most common. 1. Gastric bypass surgery (RYGB) As early as the 1950s Edward Mason reported reversal of disease in type 2 diabetic patients after gastrointestinal bypass surgery. Gastric bypass surgery began only in a few obese type 2 diabetic patients, but was associated with more serious complications such as infection, gallstones and hernias. As the technique continues to improve, RYGB is now the most commonly used procedure. Of the 200,000 surgical obesity treatments performed in 2006, 80% were performed with RYGB. RYGB can achieve satisfactory long-term weight loss, mitigate 95% of complications in patients with type 2 diabetes, and achieve clinical remission in 80% of diabetic conditions. In addition to significant weight loss, RYGB can reverse and reduce major cardiovascular and metabolic risk factors, including type 2 diabetes and lipid metabolism abnormalities, reduce long-term morbidity and mortality associated with obesity, and reduce health care costs. Bypass is currently recommended in the NIH guidelines only for those with a BMI greater than 40. However, at the 2008 EASD meeting in Rome, 78% of the attendees supported lowering the standard of surgical treatment to a BMI of 30 to benefit the more than one million diabetes-related deaths each year. 2. Laparoscopic gastric banding (LAGB) Since LAGB was first reported in 1992, it has been widely performed worldwide and was approved by the US FDA in 2001. So far, more than 800,000 cases of obesity patients have received this surgery. lAGB does not destroy the normal anatomical structure of the stomach, and has the advantages of fewer operational steps, less surgical risks, fewer and milder postoperative complications, complete restoration of the stomach body to its original state after removal of the LAGB, and lasting and obvious weight loss effect. The procedure involves binding the upper end of the stomach with an adjustable band to form a small 15 ml sac. This band can be adjusted to become enlarged or reduced in size to help the patient continue to lose weight until the desired goal is reached. Clinical remission is achieved in 30-70% of patients with type 2 diabetes via LAGB. In Asia, LAGB has been tried in some provinces and cities in China, in addition to Japan. However, this procedure requires patients to be controlled with diet. Its clinical remission rate is lower than that of bypass surgery. 3, gastric sleeve resection (LSG) gastric sleeve resection is a procedure emerging in recent years, initially used for BMI>60 super obese patients to receive bypass surgery before the preparatory surgery, the results found that about 60% of super obese patients do not need to receive bypass surgery after sleeve gastrectomy, so the procedure is used independently for weight loss surgery, resection of the large curved side of the stomach, leaving a small tubular stomach in the small curved side, without changing the access to the diet. This procedure has a certain remission rate for type 2 diabetes, with about 30%-60% reported in the literature, and diabetic patients with a BMI ≥ 35 kg/m2 have been officially listed as having an indication for surgery in the guidelines for the prevention and treatment of diabetes established at the annual scientific meeting of the American Diabetes Association in 2009. At present, the internationally recognized indications for surgery are: (1) International Health Organization (WHO) standards: BMI ≥ 40kg/ m2 or BMI ≥ 35kg/ m2 and the presence of obesity associated diseases; (2) Asia-Pacific standards: BMI > 37kg/ m2 or BMI > 32kg/ m2 and the presence of diabetes or two or more other associated diseases. In China, guidelines for the surgical treatment of obesity have also been established (2007): concomitant diseases caused by simple excess fat (metabolic disorder syndrome) are the indications for surgery in selected patients. Specifically, (1) the presence of a metabolic disorder syndrome associated with simple excess fat is confirmed and weight loss is predicted to be effective for treatment; and (2) stable or steadily increasing weight with a BMI ≥32 for more than 5 consecutive years is determined by the physician as a comprehensive determination of suitability for surgery. At the 2009 Annual Meeting of the European Association of Diabetes (EASD), an investigator reported that surgery on non-obese diabetic animals can control their diabetic condition, and in terms of short- and medium-term efficacy, it can also improve the diabetic condition in non-obese diabetic patients, and HbA1c can be reduced by about 2.5% after surgery, and more than 80% of patients can achieve blood glucose without the use of drugs Satisfactory control was achieved in more than 80% of patients without medication. The investigators therefore suggest that gastrointestinal bariatric surgery should also be the treatment of choice for diabetic patients who are mildly or moderately obese and overweight. The mechanism of gastrointestinal bariatric surgery for patients with type 2 diabetes is complex. The obvious reason is that after gastrointestinal surgery, their gastric contents or food are changed during the process of passing through the gastrointestinal tract, resulting in a reduced intake of food or a reduced ability to absorb it, as a way to reduce caloric intake and lose weight. However, for diabetic patients, the diabetic condition is significantly improved after gastrointestinal bariatric surgery before significant weight loss has occurred. As research on the pathogenesis of obesity and type 2 diabetes continues to intensify, the important role of the gastrointestinal tract as an endocrine organ and its secretion of some gastrointestinal hormones in the process of food intake and energy metabolism has received increasing attention. Studies have shown that weight loss surgery, while achieving weight loss, alters the secretion and action of gastrointestinal hormones, reduces inflammation and excessive oxidative stress in the obese organism, reduces insulin resistance and improves endothelial function. In addition, some other hormones that regulate energy metabolism, such as leptin, lipocalin and resistin, also play a corresponding role. Coronary heart disease and hypertension are the important causes of death in morbid obesity, with a mortality rate of 19.3/10,000, and tumors and diabetes are the other two important causes of death in obesity, with a mortality rate of 15/10,000 and 3.5/10,000, respectively. /Bariatric surgery can also increase the survival rate of patients with a BMI above 45. Gastrointestinal bariatric surgery can effectively reduce weight and significantly improve diabetes in a short period of time. However, there is a lack of sufficient evidence on the long-term effects and therapeutic efficacy of surgery. The results of the Swedish Obesity Study (OSO), which followed patients who underwent gastrointestinal surgery for 15 years, showed that maintenance weight loss of more than 10% was achieved in both men and women, regardless of whether binding, bypass or anastomosis was performed. The incidence of new-onset diabetes was reduced by up to 75% compared to controls at 10 years of follow-up, and clinical remission of diabetes was still achieved at 36%. A few hospitals in China, including ours, are currently performing bariatric surgery for type 2 diabetes, with initial results of significant remission, freedom from medications or reduction in insulin, etc.