P-313: Association of CGM metrics with future risk of micro- and macrovascular complications in type 1 diabetes

Abstract

Continuous glucose monitoring (CGM) is central to assessing glucose control in type 1 diabetes (T1D), including in children and adolescents, but its association with long-term complications remains insufficiently characterized in large, population-based cohorts. To evaluate whether key CGM-derived metrics are associated with micro- and macrovascular complications in individuals with T1D. We included children and adults with T1D from the Swedish National Diabetes Register with CGM measurements from 17 May 2018 to 31 December 2024, followed until 31 December 2025. Time in range (TIR), mean glucose (MG), glucose coefficient of variation (CV), time below range (TBR), and HbA1c were analyzed as time-updated mean values in Cox proportional hazards models for retinopathy, albuminuria, amputation, and cardiovascular disease. Adjusted hazard ratios (HRs) were expressed per 1 standard deviation (SD) for each glycemic metric and adjusted for clinical characteristics. TBR models were additionally adjusted for MG. Across outcome-specific cohorts, 17,186–47,613 participants without prior events were followed for a mean of 4.1–4.7 years. Lower TIR and higher MG were consistently associated with micro- and macrovascular complications (Table), with effect sizes comparable to HbA1c; TBR was independently associated with complications (Table). Among 6,916 children, mean age was 11.0 years (SD 4.3), and 1,176 developed or progressed in retinopathy. Lower TIR, higher MG, and greater TBR were associated with retinopathy: HRs 1.59 (95% CI 1.46–1.73), 1.39 (1.31–1.47), and 1.11 (1.05–1.17), respectively. Higher TIR and lower MG are strongly associated with reduced risks of micro- and macrovascular complications, including retinopathy in children, supporting their use in clinical practice and trials. The association between TBR and complications highlights the importance of minimizing hypoglycemia in T1D.