Anemia Following One Anastomosis Gastric Bypass: A Comparative Study of Diabetic and Non-Diabetic Patients.

BACKGROUND: Metabolic-bariatric surgery (MBS) is recognized as the most effective long-term intervention for obesity and its associated conditions, including type 2 diabetes mellitus (T2DM) One-anastomosis gastric bypass (OAGB), the third most common MBS, has gained popularity around the world because of its safety and efficacy; however, may be associated with nutritional deficiencies, such as iron deficiency anemia (IDA). Despite the efficacy of OAGB in achieving remission of T2DM, pre-existing T2DM may increase the risk of nutritional deficiencies after OAGB. OBJECTIVE: This study aimed to compare the prevalence and risk factors of IDA following OAGB among patients with and without T2DM. METHODS: A retrospective cohort study of 1664 patients aged 18–65 who underwent OAGB. Data on hemoglobin levels, weight loss, and comorbidities were collected preoperatively and at 6, 12, 18, 24, and 36 months post-surgery. Statistical analyses, including univariate and multivariable methods, were performed using chi-squared tests, t-tests, and logistic regression models. Factors such as age, sex, BMI, preoperative anemia, hypertension, dyslipidemia, and T2DM were adjusted for. RESULTS: Among 1,664 patients (median age: 42 years; 82.1% female; 31.5% with T2DM), 13% developed anemia. The prevalence showed no significant change after adjusting for age and BMI. Key risk factors for postoperative anemia included older age at 12 months (OR = 1.03; 95% CI: 1.01–1.06) and 18 months (OR = 1.05; 95% CI: 1.02–1.07), T2DM at 6 months (OR = 1.45; 95% CI: 1.06–1.98), higher excess weight loss at 12 months (OR = 1.01; 95% CI: 1.001–1.02), and preoperative anemia (OR = 6.28, 5.98, 5.70, 3.49, and 2.76 across follow-ups; all P-values < 0.05). Male gender and postmenopausal status consistently emerged as protective factors throughout the follow-up period (all P-values < 0.05). CONCLUSION: This study underscores an elevated risk of anemia in patients with T2DM during the first six months after OAGB. Importantly, preoperative correction of anemia did not prevent postoperative anemia after OAGB.