Laparoscopic Roux-en-Y gastric bypass (LRYGB) is the “gold standard” procedure for bariatric surgery in the United States and is a treatment for morbid obesity (BMI>40) that can achieve significant weight reduction and cardiovascular improvement. In 1992, Pories et al. were the first to report that bariatric surgery, represented by gastrointestinal bypass, could achieve rapid and durable improvement in insulin sensitivity and ultimately cure diabetes, and the number of summaries and studies of bariatric surgery as a treatment for diabetes increased. Initially, it was believed that the therapeutic effect of bariatric surgery on diabetes came from a reduction in caloric intake and weight loss. Subsequent in-depth studies found that improvement in diabetes occurred almost immediately after surgery, well before effective weight loss. Research now favors the enteric neuroendocrine theory, which states that the effects of surgery cause alterations in gastrointestinal hormones that promote insulin production and improve insulin resistance for the ultimate outcome of treating or controlling type 2 diabetes. LRYGB is a minimally invasive laparoscopic procedure that involves cutting off the distal gastric bulk, forming a small gastric sac proximally with a volume of less than 50 ml, and cutting off the jejunum about 100 cm from the flexor ligament, anastomosing the distal end of the jejunum with the remnant stomach, and performing a proximal end-lateral anastomosis with the jejunum about 100 cm below the gastrojejunal anastomosis, which alters the intestinal structure, restricts feeding and reduces This procedure alters the intestinal structure, restricts feeding and reduces food absorption. The use of LRYGB for the treatment of obese patients with type 2 diabetes is well established, but there are no specific, widely accepted criteria for the indication of the procedure. Some scholars believe that surgery is indicated for obese patients with a BMI >35 kg/m2 combined with type 2 diabetes; others believe that early intervention is advisable in patients with type 2 diabetes without serious complications and with a disease duration <5 years. What is known is that the earlier an obese patient with type 2 diabetes undergoes surgery, the more likely it is that the blood glucose will return to normal, while the longer duration of the disease has a poor outcome, which may be related to the complete recovery of β-cell function. After gastric diversion, the normal anatomical and physiological relationship is changed due to the reconstruction of the digestive tract. Therefore, the diet should be small and gradual. The gastric tube can be removed 48-72 h after the recovery of intestinal peristaltic function, and a small amount of water can be drunk on the same day, and gradually transition to preoperative diabetic fluid to semi-liquid diet. During 3-4 months after surgery, the diabetic diet should be supplemented and gradually returned to normal diet according to the blood glucose control. 3 months should be spent monitoring the change of blood glucose and gradually increasing the amount of activity, so as not to feel fatigue.