Obesity is an independent risk factor for type 2 diabetes, and about 40-60% of patients with type 2 diabetes are obese. In recent years, with the therapeutic effect of bariatric surgery on obesity, it has also been found that while reducing the patient’s weight, it also effectively improves the co-existing disorders of glucose metabolism in most patients, and bariatric surgery has taken its place in the treatment of diabetes. The principle that weight loss surgery can control blood glucose lies in: reducing food intake and absorption, thus reducing energy intake and glucose metabolic load; reducing the patient’s weight and reducing insulin resistance caused by fat accumulation due to simple obesity; changing the secretion of hormones in the gut-insulin axis after gastrointestinal tract reconstruction, thus improving glucose metabolism. Who is suitable for surgical weight loss surgery, and who can not be carried out weight loss surgery? 1.Body mass index BMI≧32kg/m2, with or without comorbidities in the Asian population with type 2 diabetes, can be considered for bariatric/gastrointestinal metabolic surgery. 2, 30 < BMI < 35kg/m2 and type 2 diabetes in Asian populations, lifestyle and drug therapy is difficult to control blood sugar or comorbidities, especially with cardiovascular risk factors, weight loss / gastrointestinal metabolic surgery should be one of the treatment options. 3. 28 < BMI < 29.9 kg/m2 in Asian populations with type 2 diabetes and centripetal obesity (waist circumference > 85 cm in women and > 90 cm in men) and at least two additional criteria for metabolic syndrome: hyperlipidemia or hypertension. Weight reduction/gastrointestinal metabolic surgery should also be considered as one of the treatment options for the above patients. 4. Patients with type 2 diabetes mellitus who are <65 years of age or in good general health with low surgical risk. Contraindications: 1. Patients with drug abuse, alcohol addiction or psychiatric disorders that are difficult to control, and patients who lack the ability to understand the risks, benefits, and expected consequences of metabolic surgery. 2. Patients with a clear diagnosis of type 1 diabetes or type 2 diabetes whose pancreatic islet beta-cell function has been largely lost. 3.Patients with combined bleeding and coagulation abnormal diseases, those whose cardiopulmonary function cannot tolerate surgery, or those whose blood sugar can be satisfactorily controlled by five carriages Bariatric surgery is mainly for metabolic diseases based on obesity, and not all people can rely on surgery to lose weight, so pre-operative examination is very necessary. We remind that patients in need must visit a specialist hospital with surgical qualifications, and not blindly.