1406-P: Rate of Age-Related EGFR Decline Differs by Insulin Dose in Type 1 Diabetes

Introduction and Objective: We previously showed that contemporaneous weight-adjusted insulin dose (insulin dose per weight, INSWT) is positively associated with eGFR in the Epidemiology of Diabetes Complications (EDC) cohort of childhood onset T1D. Here, we assessed whether the rate of age-related eGFR decline differs by INSWT. Methods: INSWT (u/kg/day) and eGFR were measured at baseline (1986-1988) and at 8 follow-up visits (2-30 years). Eligibility required age ≥18 years, baseline eGFR ≥60 mL/min/1.73 m², and ≥2 measurements. Linear mixed models with random age slopes (centered at 40 years) characterized age-related eGFR trajectories. Results: Among 449 participants (mean age 27.6 years, T1D duration 19.4 years), eGFR declined by 1.52 mL/min/1.73 m² per year (95% CI −1.65, −1.40), with no significant sex interaction. eGFR decline varied by insulin dose (−1.73 mL/min/1.73 m²/year, p<0.01) with population-average predicted trajectories showing steeper decline at higher insulin doses (Figure). Poorer glycemic control and hyperfiltration were also associated with faster decline (both p<0.0001). Conclusion: In this long-term T1D cohort, age-related eGFR decline varied by insulin dose, glycemic control, and hyperfiltration, reflecting overlapping heterogeneity in kidney aging and motivating future time-varying analyses to disentangle insulin dosing and glycemic burden in DKD progression. Disclosure M. Mosslemi: None.