It is well known that the results of UKPDS show that no treatment regimen, including insulin, can escape the outcome of secondary failure. Despite the vast amount of basic and clinical research, it is an indisputable fact that the existing regimens of diet, exercise and medication do not achieve satisfactory outcomes and long-term cures. bypass (GBP), 91% of 298 diabetic patients had their hyperglycemia reversed and 86% of 353 hypertensive patients had their blood pressure restored to normal levels. This finding has attracted great attention from academic circles, and bariatric surgery for type 2 diabetes has become a hot issue, receiving common attention from medical and surgical practitioners. 1. Clinical practice of bariatric surgery for type 2 diabetes Based on the findings of Pories et al. In 2004, Buchwald et al. collected 136 English research papers published from 1990 to 2003 and conducted Meta-analysis, which included a total of 22,094 patients, and the results showed that the total efficiency of various surgical treatments for glycemic control reached more than 80%, with a long-term complete remission rate of 76.8 The results showed that the total effective rate of various surgical treatments reached more than 80%, the long-term complete remission rate reached 76.8 %, the significant improvement reached 86.0%, and most of the patients came off diabetic medications and normalized their blood glucose and glycated hemoglobin levels. Among them, the remission rate of diabetes after biliopancreatic diversion/duodenal switch (BPD/DS) was as high as 98%, followed by Roux-en-Y gastric bypass at 84%. The combined dyslipidemia, hypertension, coronary artery disease, sleep apnea syndrome and many other metabolic abnormalities were also found to be remitted and cured. After performing biliopancreatic diversion/duodenal switch (BPD/DS), complete recovery of dyslipidemia, 81% remission of hypertension, and 95% improvement of sleep apnea syndrome were achieved. 2009 Buchwald included more updated studies and similar results were obtained. A study by KleinS showed that 1 year after gastric bypass was accompanied by a significant reduction in low-density lipoprotein-triglyceride (VDL-TG) secretion (47% +/- 4%, p<0.01) along with weight loss in patients, mainly in fatty acids derived from visceral fat. The proportion of fatty acids derived from visceral fat decreased, while fatty acids derived from subcutaneous fat did not change much. Nonalcoholic fatty liver was recovered. Another study showed that Roux-en-Y gastric bypass resulted in a significantly lower risk of cardiovascular events in patients, with baseline levels and 10-year follow-up results of 6 +/- 5% and 4 +/- 3%, respectively (P<= 0.0001), and a lower risk of cardiovascular events in postoperative patients than in the sex- and age-matched general population during the same period (5 +/- 4% vs 11 +/- 6% in men, P< 0.0001; women 3 +/- 3% vs. 6 +/- 4% P<0.0001). Framingham risk score results showed a 39% reduction in men and a 25% reduction in women. 2. Risk-benefit analysis of surgery The role of bariatric surgery in the treatment of type 2 diabetes and metabolic syndrome is unquestionable; however, all surgical procedures carry a certain risk, but this risk is only meaningful when compared with diabetic impairment. Risk-benefit assessment is therefore an important issue in the selection of therapeutic surgery. The first concern is the risk of death from the surgery itself. Dimick et al. reported the risk of death from seven common surgical procedures, ranging from hip arthroplasty with a mortality rate of 0.3% to craniotomy with a mortality rate of 10.7%, while the mortality rate from gastrointestinal diversion was comparable to that of hip arthroplasty. In contrast, at postoperative follow-up, postoperative mortality was significantly reduced (30% to 90%) compared with non-operative diabetic patients of the same baseline age and body mass index level. in a retrospective study conducted by Adams et al. in 2007 with 18-year follow-up, 7925 obese patients who underwent RYGB compared with the same number of non-operative patients of the same baseline sex, age and body mass index had a mean 40% reduction in risk of total mortality over 7.1 years (3.76% and 5.71% per year, respectively; P<0.001); 92% reduction in mortality from diabetes-related complications (0.4% and 3.4% per year, respectively; P=0.005); 56% reduction in risk of cardiovascular disease (2.6% and 5.9% per year, respectively; P=0.006); and 60% reduction in cancer mortality (5.4% and 5.9% per year, respectively; P=0.006). 60% (5.5% and 13.3% per year, respectively, P=0.001). This shows that the benefit of postoperative mortality reduction is much greater than the risk of death from surgery itself, and bariatric surgery is still an effective way to treat the comprehensive management of metabolic syndrome in obese diabetic patients. 3, the mechanism of action of surgery for the treatment of type 2 diabetes is explored Weight loss is the original purpose of surgery, and the digestive tract is treated in a different way to limit intake, reduce absorption and consume its own excess fat to achieve the purpose of weight loss. This makes surgery the only long-term effective way to treat morbid obesity. So, does postoperative remission of type 2 diabetes glucose occur with weight loss? The results of the study are intriguing, however, as glycemic recovery in diabetic patients after RYGB occurred much earlier than significant weight loss, and Rubino reported that patients all returned to normal blood glucose levels 1 month after GBP, when weight loss was far from satisfactory. The literature shows that the rate of diabetes remission after gastric banding is significantly lower than that of RYGB and GBP for the same bariatric surgery, all of which suggest that recovery of type 2 diabetes is not directly related to weight loss. There may be a mechanism of glucose lowering other than bariatric. The entero-islet axis is a hot spot in endocrine and gastrointestinal surgery research in recent years. It has been suggested that various hormones secreted by the gastrointestinal tract are related to the regulation of glucose metabolism, including cholecystokinin (CKK), gastric inhibitory polypeptide (GIP), glucagons-likepeptide-1 (GLP -1), ghrelin, leptin, peptide YY (PYY), adiponectin (ADPN), etc. There are three main hypotheses: (1) duodenal-jejunal hypothesis: GIP is synthesized and released by K cells in the duodenum and proximal jejunum, and there is often excessive secretion of GIP in diabetic patients, which is associated with the development of insulin resistance. In contrast, after GBP (or duodenojejunostomy), the stimulation of nutrients to the proximal small intestine is reduced or stopped, the release of GIP by K cells is reduced, thus alleviating insulin resistance, and long-term cure of type 2 diabetes is obtained. (2) Distal ileum hypothesis: GLP-1 is synthesized and released by L cells in the distal ileum and colon, which has a pro-insulin secretory effect and increases islet regeneration and reduces apoptosis. pYY is also a hindgut hormone released mainly by L cells in the distal ileum after meals, which acts on the arcuate nucleus of the hypothalamus to inhibit the release of neuropeptide Y, producing a feeling of satiety and inhibiting gastric emptying and gastrointestinal motility, thus suppressing appetite and reducing Weight loss. After GBP or biliopancreatic diversion, undigested or partially digested food enters the distal ileum early, stimulating L cells to secrete GLP-1 and PYY, causing an increase in insulin secretion and suppressing appetite, reducing energy intake, and thus lowering blood glucose. One study showed that feeding stimulated increased GLP-1 and PYY concentrations in patients after RYGB, peaking 30 minutes after meals and significantly higher than other bariatric procedures such as BPD and GB. In summary, surgery opens a new avenue for the treatment of type 2 diabetes.