Diabetes has been a hot topic worldwide in the past few years, especially in China, where the number of patients has exceeded 100 million, and there is a trend of younger development, so we have to pay attention to it. Many data show that obesity is one of the most important factors in the treatment of diabetes. How does obesity cause diabetes? After we eat, our body converts part of the food into glucose through the digestive system into our blood to provide the energy needed for the normal functioning of various tissues and organs. But our body can’t use that much at one time, so it needs to convert the excess glucose into other forms such as fat and store it for later use, and only insulin in our body can do this job. Insulin is a hormone secreted by the pancreas, and it is secreted according to the changes in our blood sugar, so in a healthy body, the more glucose we get from food, the more insulin the pancreas secretes, which keeps our blood sugar in a stable state. But any organ has its limits, and overuse will only make it perform worse or even fail outright. If we overeat for a long time, forcing the body to secrete a lot of insulin to regulate blood sugar, the pancreas will fail due to long-term overdraft. Another result of chronic overeating is a rapid rise in fat content, which is what we call getting fat, and excess fat is one of the major causes of diabetes. There are many studies that show that fat participates in the inflammatory response of the body, increases insulin resistance and makes insulin less effective, which accelerates even more the overdraft of the pancreas and accelerates the evolution of diabetes. The main causes of diabetes due to obesity are overeating and high insulin resistance due to too much fat, and it is from these two aspects that sleeve gastric surgery is performed to treat diabetes. After sleeve gastric surgery, the patient’s diet is restricted, which reduces the amount of blood sugar the body gets from food; at the same time, after sleeve gastric surgery, the patient loses a lot of extra weight within a year, which greatly reduces the insulin resistance caused by obesity and enhances the effect of insulin. It has also been pointed out that because most of the stomach is removed during sleeve surgery, the hormone secretion is also changed, which further enhances the effect of blood sugar control. Still, in terms of pure glucose control, there is a slight gap between sleeve gastric and gastric bypass surgery, which is only suitable for those patients with milder forms of diabetes. At the same time, however, the effectiveness and safety of both procedures are very dependent on the surgeon performing them. Both sleeve gastric and gastric bypass are delicate gastrointestinal procedures that require a lot of practice to ensure the results and safety of the procedure. An experienced surgeon is more mature than a novice surgeon in both surgical operation and response to emergencies, which is why surgeries performed by those who are renowned surgeons tend to have better results.