Among 151 adults with obesity and type 2 diabetes undergoing bariatric surgery, 79.5% achieved diabetes remission during follow-up, with 60.3% maintaining remission at five years. Sustained remission was independently predicted by shorter pre-surgical diabetes duration (aOR 0.980 per month, p<0.001), lower baseline HbA1c (aOR 0.671 per 1% increase, p=0.002), and higher preoperative BMI (aOR 1.120 per kg/m², p=0.008). Of those who initially remitted, 22.5% relapsed — mostly between years four and five — with longer diabetes duration and higher HbA1c elevating relapse risk, while greater one-year excess weight loss reduced it by 25% per 10-percentage-point gain.
These findings reinforce a consistent message in metabolic surgery literature: timing is everything. Early intervention — before glycemic burden accumulates and beta-cell function is exhausted — dramatically improves the odds that remission will last. The relapse clustering between years four and five is a clinically useful signal, suggesting intensified metabolic monitoring around that window rather than assuming surgical success is permanent. The higher preoperative BMI association with sustained remission is counterintuitive but likely reflects greater adiposity-driven insulin resistance that resolves more completely with weight loss. Limitations include the retrospective single-center design, modest cohort size, and Spanish referral-center demographics that may limit generalizability. Nonetheless, this study adds quantified, multivariable precision to the practical conversation clinicians should be having with T2D patients about the optimal surgical window — an incrementally useful, confirmatory contribution.