Metabolic surgery significantly improves metabolism-related diseases such as diabetes, hyperlipidemia, hypertension, etc. A hybrid procedure is now common internationally: jejuno-gastric bypass. By restricting the gastric volume, it causes a series of changes in the level of glucose-regulating hormones, often resulting in significant improvement in glycemic control before the patient loses weight, and is the most common weight loss surgery internationally. Possible mechanisms of weight loss surgery to relieve type 2 diabetes: 1. Calorie restriction and weight loss: Gastric pro-growth hormone is mainly secreted by gastric fundic cells and acts on hypothalamus to promote appetite, increase food intake, inhibit energy consumption and lipolysis, and inhibit insulin secretion by pancreatic islet cells through paracrine mode. After surgery, its secretion level showed a significant decrease. Postoperative decreased appetite and reduced gastric volume both restrict caloric intake and reduce body weight, both of which can improve insulin sensitivity to some extent. The improvement of insulin resistance and diabetes can often last up to 3 years or even longer after surgery. 2, foregut effect: The “foregut hypothesis” believes that after eliminating the stimulation of nutrients to the gastroduodenum, certain antagonistic insulin signals in the gastrointestinal tract are reduced, thus promoting the synthesis and/or release of insulin, and even increasing insulin sensitivity. 3. Hindgut effect: The “hindgut hypothesis” suggests that after gastric bypass, food is rapidly transported to the distal small intestine, which promotes the production of enteric-derived endocrine hormones and thus improves glucose metabolism. The enteric endocrine hormones include GLP-1, gastric inhibitory peptide (GIP), and PYY, among which GLP-1 is secreted by small intestine L cells and promotes insulin release through β-cell membrane-specific receptors under glucose stimulation, reduces β-cell apoptosis, and delays gastric emptying and prolongs satiety time. Mechanisms of metabolic surgery for type 2 diabetes 4. Bile acids: The formation of Roux loops after gastric bypass increases the concentration of bile acids in the intestinal lumen, and bile acids activate G protein-coupled bile acid receptors on the surface of L cells, promoting remission of type 2 diabetes through upregulation of GLP-1 secretion. Roux-en-Y gastric bypass is particularly effective in the treatment of obesity and type 2 diabetes mellitus. Although postoperative metabolic improvements are in part attributable to weight loss, the earlier onset of postoperative glycemic control than weight loss, as well as changes in insulin sensitivity and intestinal hormones, suggest that changes in the physiological environment of the human GI tract induced by weight loss surgery are more important mechanisms. type 2 diabetes is increasingly seen as a surgically curable gastrointestinal disease.