Obesity and type 2 diabetes have become serious problems affecting the health of the general population, and the two diseases are independent of each other and are linked in some way. Surgical treatment is the only way to achieve long-term and stable results in patients with severe obesity. Although weight reduction and metabolic surgery is not yet accepted by all internists in China, it has become a focus of attention for endocrine metabolic physicians, and the number of cases of obesity and diabetes treated with surgery in China has steadily increased in recent years, and its weight loss and glucose-lowering effects have been far superior to those of medical drug therapy. With clinical work, there is increasing evidence that bariatric surgery not only reduces weight but also improves or even cures a variety of metabolic diseases associated with obesity, such as sleep breathing syndrome (snoring, breath-holding), polycystic ovary syndrome (infertility), hyperuria, hypertension, and especially type 2 diabetes. The indications for surgical treatment of obesity and type 2 diabetes are constantly being revised as they are applied in clinical practice. In China, with the recent development of surgical treatment of obesity and diabetes in the last 10 years or so, the indications and contraindications have gained their own experience. In 1991, the National Institutes of Health (NIH) published the first consensus on bariatric surgery, which defined the conditions for surgery in obese patients as: body mass index (BMI) >40 or 35-40 with severe comorbidities (including diabetes) and able to tolerate surgery. This consensus has an important role in standardizing the clinical indications for surgery and in evaluating the effectiveness and risks of surgical treatment. The consensus uses BMI as a criterion for surgical treatment and restricts surgical treatment to severely obese patients. Of course, for the indication of obesity surgery, BMI is the main reference index in Europe, America and Asia Pacific, but the specific criteria are different. The indications for surgery in Europe and the United States are BMI ≥ 40 or ≥ 35 and the presence of some obesity-related co-morbidities, while the more acceptable indications for surgery in the Asia-Pacific region are BMI ≥ 37 or ≥ 32 and the presence of some obesity-related co-morbidities. The number of extremely obese people in the Asia-Pacific region is less than that in Europe and the United States, and the type of obesity is mostly abdominal obesity, and obesity-related metabolic diseases can occur at a relatively low BMI level. Therefore, the WHO Asia-Pacific Working Group recommended that the overweight and obesity criteria in the Asia-Pacific region are BMI≥23 and ≥25 respectively, but the Chinese Ministry of Health announced in 2003 that the obesity criteria in China are BMI>28, or waist circumference index: men>90cm, women>85cm. For the surgical treatment of obesity, it is necessary to emphasize the role of BMI in the indication of surgery and the determination of efficacy. From the point of view of surgery, if the associated morbidity caused by obesity has been relieved or disappeared after surgery, even if the patient is still overweight or mildly obese, the treatment purpose has been achieved. Of course, if the weight is also reduced to the normal range, the efficacy of surgery is more obvious and patient satisfaction is higher. As an auxiliary reference in the medium and long term. (1) The indications for surgical treatment of obesity are clearly standardized: (1) The presence of metabolic disorder syndrome related to simple fat excess is confirmed, such as type 2 diabetes, cardiovascular disease, fatty liver, lipid metabolism disorder, sleep apnea syndrome, etc., and weight loss is predicted to be effective treatment. (2) Waist circumference ≥ 90 cm in men and ≥ 80 cm in women; dyslipidemia, i.e., triacylglycerol (TG) ≥ 1.7 mmol/L. and/or) fasting blood high-density lipoprotein cholesterol (HDL-ch): < 0.9 mmol/L in men and < 1.0 mmol/L in women. (3) Stable or steadily increasing body weight for more than 5 consecutive years with a BMI ≥ 32 (should refer to the patient The coefficient calculated from the weight with confirmed records under normal conditions and the height at that time, while special circumstances such as within 2 years after pregnancy should not be used as a basis for selection). (4) Age 16 to 65 years. For those who are >65 years old, since the complications related to obesity are persistent and complicated, the pros and cons of surgery should be weighed according to the preoperative examinations before deciding whether to operate or not. (5) The non-surgical treatment is not effective or cannot be tolerated. (6) No alcohol or drug dependence, no serious mental or intellectual impairment. (7) Patients understand the surgical procedure of bariatric surgery, understand and accept the risk of potential complications of surgery, understand the importance of postoperative lifestyle and diet changes to postoperative recovery and have the ability to tolerate them, and can actively cooperate with postoperative follow-up. A large number of clinical data show that bariatric surgery has good efficacy in the treatment of metabolic disorder syndrome, and the effect on blood glucose control is very obvious, even curing the concomitant type 2 diabetes. Several clinical studies have shown that bariatric surgery is effective not only for severe obesity, but also for non-obese patients with type 2 diabetes. Therefore, in 2010, an expert consensus on surgical treatment of type 2 diabetes was reached after discussion among medical surgeons and a related consensus was published, and also in 2011, the Diabetes Division proposed the idea of surgical treatment of type 2 diabetes for the first time in the diabetes treatment guidelines. The Expert Guideline on Surgical Treatment of Diabetes Mellitus (2010) suggests that patients with type 2 diabetes mellitus who have experienced poor results or cannot tolerate long-term non-surgical treatment may be considered for weight loss metabolic surgery if there are no obvious contraindications to surgery. At the same time, the guideline also defines factors such as the duration of diabetes, pancreatic islet cell function, and age that affect the outcome of surgical treatment for type 2 diabetes. Since most obese patients in China are abdominally obese and have a higher risk of cardiovascular and cerebrovascular accidents and other complications, it is recommended that surgery should be considered more actively when the waist circumference is ≥90 cm in men and ≥80 cm in women. For normal or overweight patients with combined type 2 diabetes (BMI<28), although preliminary data show that surgical treatment also has better results in this population, further randomized controlled clinical studies and validation based on fully informed consent are still required and should not be promoted at this time. < p=""> In 2011, the American Diabetes Association (ADA) guidelines for diabetes recommended that bariatric surgery be considered for patients with type 2 diabetes with a BMI ≥35, especially if the diabetes or associated comorbidities remain uncontrolled with lifestyle and pharmacologic therapy. Patients with type 2 diabetes who have undergone bariatric surgery should undergo long-term lifestyle counseling and medical monitoring. The guidelines are generally consistent with the indications for bariatric surgery in Europe and the United States. In the same year, the International Diabetes Federation (IDF) issued a statement on bariatric surgery for the treatment of obesity combined with type 2 diabetes, which considers BMI for patient selection and defines BMI clearly as patients with type 2 diabetes with BMI ≥35 (32.5 in Asia), and for patients with BMI 30 to <35 (27.5 to <32.5 in Asia). Surgery may also be considered if the target is not achieved with appropriate pharmacological therapy, especially in the presence of other major cardiovascular disease risk factors. This statement advances the ADA guidelines for the surgical treatment of mildly obese patients with type 2 diabetes who are not well treated medically or who have other serious co-morbidities. In 2011, the Expert Consensus on Surgical Treatment of Diabetes, jointly published by the Chinese Medical Association Diabetes and the Chinese Society of Surgery, provided the following indications for surgery: (1) Patients of Asian descent with type 2 diabetes with a BMI ≥ 35 and with or without complications may be considered for weight loss or gastrointestinal metabolic surgery; ? (2) Weight loss or gastrointestinal metabolic surgery should be a treatment option for Asian patients with type 2 diabetes with a BMI of 30 to <35 who have difficulty controlling blood glucose or comorbidities with lifestyle and pharmacologic therapy, especially if they have cardiovascular risk factors; (3) BMI of 28 to <30 2="">85 cm, waist circumference >90 cm in men) who meet at least 2 additional criteria for metabolic syndrome (high TG, low HDL-ch (4) For adolescents with a BMI ≥ 40 or ≥ 35 with severe comorbidities, and who are ≥ 15 years of age, skeletally mature, and in Tanner developmental class 4 or 5, laparoscopic adjustable gastric banding (LAGB) or Roux-en-Y gastric bypass (RYGB) may also be considered as a treatment option; (5) In patients with type 2 diabetes with a BMI of 25 to <28, the procedure should be performed with the patient's informed consent and strictly according to the study protocol, but the nature of these procedures should be considered purely as part of a pilot study with prior ethics committee approval only and should not be widely disseminated; (6) Patients with type 2 diabetes mellitus who are <60 years of age or in good general health and at low risk for surgery. In 2014, the American Association of Clinical Endocrinologists (AACE) proposed a new "framework" for the diagnosis and management of obesity, suggesting that the definition of obesity should change from "BMI-centered" to "obesity-related complications. The definition of obesity should be changed from "BMI-centered" to "obesity-related complications. Bariatric surgery may be considered for patients in obesity class 2 (BMI ≥ 25 with at least one severe obesity-related complication). The new diagnosis is based not only on BMI, but also on the health effects of weight gain. This is a breakthrough from the BMI-centric concept and openly presents the health impact of obesity-related complications. It is evident that the remission or disappearance of metabolic disorder syndromes is the ultimate goal in the treatment of obesity. According to most studies in the literature, the main factors that influence the outcome of surgical treatment of type 2 diabetes are: (1) the better the function of pancreatic islet B cells, the better the outcome; (2) the shorter the duration of the disease, the better the outcome; (3) the younger the age, the better the outcome; and (4) the higher the BMI, the better the outcome. Therefore, the preoperative evaluation of diabetes is more important and requires detailed assessment and exclusion of autoimmune diabetes (LADA), as well as type 1 diabetes. With the advancement of clinical care, the expansion of surgical samples, and the extension of postoperative follow-up years, bariatric surgery for type 2 diabetes is rapidly developing both domestically and internationally, and the indications for bariatric surgery are constantly being revised. For patients with type 2 diabetes with BMI <27.5, although the current preliminary data show that surgical treatment has good results in this group, further research and demonstration are needed, and it is not advisable to promote it for the time being. For this group of patients, medical treatment should be chosen first. If medical treatment is not effective or not tolerated by the patient, and if the patient strongly requests surgical treatment, surgical treatment can be performed according to the pathway of the clinical trial after sufficient information. For patients with BMI <24, surgery is generally not considered unless the patient has other indications for surgery. It is believed that with the multicenter studies on the surgical treatment of normal weight type 2 diabetic patients, the trend of the future revision of the indications should be to study in depth the important influencing factors related to the surgical efficacy of type 2 diabetes mellitus, to classify type 2 diabetes mellitus in detail, and to identify patients suitable for surgery among the low weight diabetic patients to improve the surgical efficacy. The indications for surgery in the treatment of diabetes mellitus are only part of the surgical aspect, but also the safety of surgery, the different ways of surgery, and the level of postoperative management to avoid postoperative complications.