The effectiveness of surgical treatment of diabetes mellitus is related to various factors such as the duration of its diabetes mellitus, islet cell function, and patient’s age. First, the patient’s body mass index should be ≥ 28 kg/m2; second, the duration of the disease should not be greater than 15 years to ensure that their islet reserve function is above 1/2 of the lower limit of normal and c-peptide is ≥ 1/2 of the lower limit of normal; in addition, the patient is usually not older than 65 years. How much do you know about gastric bypass surgery? What are the pros and cons of gastric bypass surgery? ”Gastric bypass surgery” is a gastrointestinal rerouting surgery that changes the physiological flow of food, which is reflected to the brain through the surgery of the stomach. The hypothalamus of the brain has a leptin center and a glucose regulation center, thus eliminating insulin resistance and restoring the function of the pancreas. Specifically, the function of the digestive tract after surgery is divided into two areas: 1. Food diversion zone: refers to most of the stomach, duodenum and part of the proximal jejunum, which is no longer stimulated by food after surgery, resulting in a decrease in the secretion and synthesis of “diabetogenic factors”. 2. This section of the digestive tract receives undigested or incompletely digested food in advance, resulting in an increase in the secretion of hormones, which increases the sensitivity of insulin through the “intestine-islet axis” and promotes the secretion of insulin, thus achieving the effect of blood sugar control. Advantages of gastric bypass surgery: 1. Patients’ blood glucose decreases and stabilizes at normal level; 2. Avoid lifelong medication; 3. consumption of health resources. The disadvantages of gastric bypass surgery: Any surgery has risks and potential complications, and gastric bypass surgery is the same, and when diabetic patients need surgery, the risk is greater than the average person. When blood sugar is poorly controlled, surgery can induce complications such as ketoacidosis or hyperosmolar coma. Hyperglycemia can also lead to incomplete healing of the surgical incision and easy infection. After surgery, some patients have gastroparesis, unbalanced gastrointestinal recovery, bloating, and inability to eat. Because the surgery is gastric decompensation, but part of it will usually recover with treatment. Disadvantage one: changes in the gastrointestinal digestive tract, the large open gastric sac cannot be examined by gastroscopy and can only be examined by CT and other examinations or explored under laparoscopy, so patients with a family history of gastric cancer or recurrent gastric ulcers need to be considered carefully. Disadvantage 2: Postoperative anastomotic ulcers will occur, mainly in those patients who smoke and drink. Disadvantage three: the operation is relatively complex and requires high technical level of doctors and high laparoscopic skills, so not all doctors are suitable for the operation. Disadvantage 4: Long-term vitamin and mineral supplementation is required after surgery. Patients are advised to take regular multivitamin supplements after surgery, especially iron, calcium, etc.