P-146: Long-term glycemic trajectories and behavioral determinants during three years of advanced hybrid closed-loop therapy in youth with type 1 diabetes

Introduction Data on the persistence of glycemic benefits beyond the first year of automated insulin delivery are scarce, especially in large pediatric multicenter settings. Objectives This study assessed long-term effectiveness and determinants of sustained optimal control over three years of MiniMed™ 780G use in young individuals with type 1 diabetes. Methods In this real-world, longitudinal multicenter study, 359 participants (median age 12.2 years; 50.9% female) from 20 Italian pediatric centers were followed for 3 years after MiniMed™ 780G initiation. Glucose outcomes, insulin delivery patterns, and system settings were evaluated at 1, 2, and 3 years. Trends over time were analyzed using linear mixed-effects models, and predictors of achieving time in tight range (TITR ≥50%) at 3 years were identified through multivariable logistic regression. Results Median time in range (TIR) remained within recommended targets, with a slight decline from 75% at year 1 to 74% at year 3 (p=0.002). Automated correction boluses progressively increased, while user-initiated boluses and carbohydrate entries decreased (p<0.001). Participants with higher 1-year TIR showed a gradual decline over time alongside a greater rise in automated corrections (interaction p<0.001) (Figure 1). At 3 years, greater SmartGuard use (OR 1.12, p=0.008), optimized system settings (OR 2.99, p=0.013), and fewer automated corrections (OR 0.85, p<0.001) independently predicted TITR ≥50%. Conclusions MiniMed™ 780G maintains effective glycemic control over three years. However, increasing dependence on automation and reduced user engagement may limit optimal outcomes, underscoring the importance of continuous education and device optimization.