Preoperative glycemic control and outcomes following metabolic and bariatric surgery in patients with type 2 diabetes

Abstract Background Metabolic and bariatric surgery (MBS) is an effective treatment for patients with obesity and type 2 diabetes (T2D). Preoperative T2D severity may influence perioperative safety and T2D outcomes after MBS. Methods A retrospective analysis of a single-center database of adults with T2D who underwent MBS between January 2017-May 2024. Patients were divided into controlled and uncontrolled T2D groups according to preoperative T2D status. Baseline characteristics, perioperative complications, and mid-term outcomes were analyzed and compared. Results Among 203 patients included, 124 had controlled T2D and 79 had uncontrolled T2D. Patients with uncontrolled T2D were older (52.4 ± 10.2 vs. 48.1 ± 11.5 years, p = 0.03) and had a worse baseline metabolic profile, including higher HbA1c levels (8.25 ± 0.93% vs. 6.09 ± 0.45%, p < 0.001), higher fasting glucose levels (155.8 ± 39.9 vs. 121.0 ± 24.5 mg/dL, p < 0.001), and greater insulin use (35.4% vs. 5.6%, p < 0.001). Overall, 90-day complications were insignificantly higher in the uncontrolled group (13.9% vs. 7.3%, p = 0.053). At a mean follow-up of 41.4 ± 28.0 months, total weight loss was comparable (28.02%±12.51 vs. 27.28%±11.03, p = 0.71). Patients with uncontrolled T2D had higher antidiabetic medication use (44.5% vs. 19.4%, p < 0.001), higher insulin use (8.3% vs. 1.2%, p = 0.034), and higher HbA1c levels (6.20 ± 0.92% vs. 5.43 ± 0.52%, p < 0.001). T2D remission was higher among patients with controlled T2D (79.5% vs. 51.8%, p < 0.001). Conclusion Patients with controlled T2D before MBS achieved higher remission rates than patients with uncontrolled T2D, despite comparable weight loss outcomes. Interestingly, patients with uncontrolled T2D still experienced meaningful glycemic improvement and reduced medication burden, supporting the benefit of MBS in this high-risk group.