<h4>Background</h4>To observe the changes in bile acid synthase activity, conjugation enzyme gene and intestinal mucosal barrier function (D-LA, Zonulin, MFG-E8) in patients with type 2 diabetes mellitus (T2DM) after bariatric and metabolic surgery (BMS), and to provide an objective opinion on the clinical optimisation of BMS.<h4>Methods</h4>127 patients with T2DM who had received BMS treatment at our hospital from October 2023 to August 2024 were included in the study, and weight loss glucose-lipid metabolism was detected before surgery and 6 months after surgery. This evidence concerns the gene HP and diabetes mellitus.