Increased survival reveals new paradigms in diabetic macular edema among patients with type 1 diabetes

Treatment and monitoring developments markedly improved the survival rate of individuals with type 1 diabetes (T1D). Nevertheless, literature remains scarce on long-term incidence of diabetic macular edema (DME) in this population, with the major study existing in the field - Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) - reporting its development at 30 years of disease. We aimed to estimate the long-term risk of DME and associated factors in a representative sample of type 1 diabetic patients.

This retrospective cohort study included 235 patients with T1D from a tertiary center in Portugal. Data on demographics and clinical characteristics were extracted from digital medical records and analyzed using descriptive statistics. Kaplan-Meier survival analysis was used to assess DME development over the follow-up period. Potential predictors of DME, including age at T1D diagnosis, duration of T1D, glycated hemoglobin (HbA1c), body mass index (BMI), severity of diabetic retinopathy (DR), systolic and diastolic blood pressure (SBP and DBP), and smoking habits, were analyzed using multivariate Cox regression.

The overall prevalence of DME was 18.7%. The cumulative risk of developing DME escalated from 7.6% at 20 years to 51.1% at 65 years of T1D duration (p < 0.001). Patients with severe or proliferative DR had a significantly higher prevalence of DME (p < 0.001). The prevalence of microvascular complications was higher in the DME group (54.5% versus 19.4%, p < 0.001). Age at T1D diagnosis and DR severity were the strongest predictors of DME, with hazard ratios of 1.03 (95% CI [1.00-1.06]; p = 0.029) and 1.46 (95% CI [1.20-1.77]; p < 0.001), respectively. HbA1c and SBP were associated with DME in univariate analysis but lost significance in multivariate models.

This study highlights the time-dependent nature of DME development in T1D, with a marked increase in risk beyond 20 years of disease duration, a pattern that appears to differ from what is typically observed in T2D. DR severity was a key predictor of DME. DME was associated with the presence of microvascular, but not macrovascular complications. These findings emphasize the importance of tailored surveillance strategies to improve outcomes in this high-risk population.