Inclusion Criteria:  21-65 years old, Male/Female, East Asian population 50 kg/m2≥BMI≥27.5kg/m2 Type 2 diabetes duration ≥6 months HbA1c≥7.0% Currently receiving one or more oral/injectable hypoglycemic drugs (insulin /glucagon-like peptide-1 receptor agonist) Recommendation for OAGB/RYGB evaluated by a multidisciplinary team  Exclusion Criteria:  Underwent gastrointestinal surgery (gastric/duodenal surgery or bariatric surgery) Fasting C-peptide level lower than 1/2 normal minimum Active gastrointestinal ulcer is present Helicobacter pylori infection is present A history of serious cardiovascular and cerebrovascular diseases (myocardial infarction, stroke, etc.) A history of cirrhosis (Child-Pugh≥A) A history of chronic kidney disease (eGFR )< 60 ml/min / 1.73 m2) Inflammatory bowel disease is present (ulcerative colitis, Crohn's disease) Chronic anemia is present, Hgb for male <100g/L, for female <90g/L A desire to conception during the study period Uncontrolled mental and psychological disorders are present Expected survival<5 years of end-stage disease or previous/current malignant tumor Participated in clinical studies/trials that have the conflict of interest with the study Unable to understand, refuse to participate and sign the informed consent