The role of metabolic and bariatric surgery (MBS) in adults with type 1 diabetes mellitus (T1DM) remains uncertain, particularly regarding glycaemic outcomes and safety. A systematic review and meta-analysis published in Diabetic Medicine evaluated weight, glycaemic control, insulin requirements, and postoperative complications following MBS in adults with T1DM.

This PRISMA-compliant and PROSPERO-registered analysis included studies identified through major databases. A total of 22 studies involving 1324 adults were analyzed, with a mean age of 42.2 years and a mean follow-up of 31.6 months. Among participants with reported sex, 74.6% were women. A total of 1304 procedures were performed, most commonly Roux-en-Y gastric bypass (44.5%) and sleeve gastrectomy (39.2%), followed by adjustable gastric banding (13.0%).

Meta-analysis showed reductions in body weight (mean difference 29.55 kg; 95% CI 25.72-33.39) and BMI (11.35 kg/m²; 95% CI 10.36-12.34). HbA1c decreased modestly by 4 mmol/mol (95% CI 2.05-6.78). Insulin requirements declined by 43%-48% (0.20 U/kg; 95% CI 0.13-0.26). Postoperative complications included diabetic ketoacidosis in 8% and severe hypoglycaemia in 4%, with any complication reported in 4% of patients.

These findings indicate that MBS results in substantial weight loss and reduced insulin requirements in adults with T1DM, while glycaemic improvement appears limited. The observational evidence base and variable safety reporting warrant cautious interpretation, and further prospective studies are needed.