Supplementary Material for: Determinants of Diabetes Remission and Relapse Following Sleeve Gastrectomy and Gastric Bypass: A 2- and 5-Year Follow-Up Study

Introduction: Bariatric surgery is an established treatment for obesity and has been shown to improve glycemic control and frequently induces remission of type 2 diabetes mellitus (T2DM). However, the long-term sustainability of remission remains uncertain, as relapse may occur over time. This study evaluated short- and long-term remission rates and identified factors associated with remission durability and relapse.
Methods: A retrospective cohort study was conducted which included 186 patients with obesity and Type2 diabetes who underwent sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) between January 2009 and December 2020 at University Hospital Ayr. Diabetes remission was defined as HbA1c < 6.0% without anti-diabetic medication use, assessed at 2 years (short-term) and 5 years (long-term). Multivariable logistic and Cox regression models were used to identify factors associated with remission and relapse.
Results: Two- and five-years post-surgery remission rates were 57.5% and 36.4%, respectively. Shorter duration of diabetes (OR 0.86, 95 % CI 0.76 - 0.96; p=0.009), lower preoperative HbA1c (OR 0.61, 95% CI 0.43 – 0.87; p=0.005) and not using anti-diabetic medications before surgery (p<0.05) were all associated with a higher likelihood of diabetes remission at 2 years. Of 107 patients who achieved remission at 2 years, 33.4% experienced diabetes relapse by 5 years. Age (HR 1.06; 95% CI 1.01 – 1.12; p<0.015) and use of anti-diabetic medications (p<0.05) were identified as significant factors associated with diabetes relapse.
Conclusion: Bariatric surgery is effective in achieving early remission of T2DM; however, one-third of patients experience relapse within five years. A more favourable preoperative metabolic profile and younger age play a crucial role in remission durability. These findings highlight the importance of long-term follow-up and individualised patient counselling on expected diabetes outcomes after bariatric surgery.