To investigate the long-term efficacy and safety of gastric bypass(Roux-en-Y gastric bypass, RYGB)on patients with type 2 diabetes mellitus(T2DM).

T2DM patients who received RYGB in Beijing Tiantan Hospital Affiliated to Capital Medical University were retrieved from Bariatric and Metabolic Surgery Database. Cases with complete data after 5 years of postoperative follow-up were selected to analyze the preoperative and postoperative weight, blood glucose, and combined changes in indicators such as disease and nutrition, as well as the occurrence of long-term complications of surgery.

Thirty-seven patients with T2DM undergoing RYGB were enrolled. The mean follow-up was 6.2(5.0-9.0)years. Five years after operation, body weight and glycosylated hemoglobin(HbA1c) of all were significantly lower than those before operation, and the differences were statistically significant (all P values were less than 0.05). Only 29.7% of the patients used hypoglycemic drugs 5 years after operation, which was significantly lower than that before operation, and the difference was statistically significant(P<0.01). The complete remission rate of T2DM after 5 years was 29.7%. Compared with before operation, triglyceride(TG)was significantly reduced, high-density lipoprotein(HDL)was significantly increased, and the number of abnormal lipid metabolism and abnormal liver function were significantly reduced at 5 years after operation, and the differences were statistically significant(P value are less than 0.05). In terms of nutrition, the level of ferritin at 5 years after operation was significantly lower than that before operation, and the difference was statistically significant(P<0.05). Hemoglobin, albumin, folic acid, and vitamin B₁₂ were all lower than those before operation, but the differences was not statistically significant(all P values were greater than 0.05). Five years after operation, 1 case(3.0%)was accompanied by symptoms of recurrent incomplete intestinal obstruction, 2 cases(6.0%)developed new gallbladder stones, and 6 cases(18.2%)developed iron deficiency anemia.

In the long run, RYGB is safe and effective for T2DM patients. After RYGB, there are risks such as weight, blood sugar rebound, and nutritional disorders. Postoperative follow-up, diet and medication guidance should be paid attention to. Patients after RYGB should be supplemented with iron, vitamins and various trace elements preventively.