Racial and microvascular determinants of progression to treatment-warranted diabetic eye disease

OBJECTIVE: To evaluate racial and ethnic disparities in progression from non-proliferative diabetic retinopathy (NPDR) to treatment-warranted diabetic eye disease (TW-DED), and the influence of microvascular diabetic complications, including nephropathy (DN) and foot ulcers (DFU). METHODS: We conducted a retrospective cohort study using a federated electronic health records network (2005-2025) of adults ≥40 years with type 2 diabetes and NPDR, excluding those with prior TW-DED. Participants were stratified by race/ethnicity (White, Hispanic, Black, Asian, Other) and by DN and/or DFU status. Propensity score matching (1:1) balanced baseline characteristics. The primary outcome was progression to TW-DED, defined as proliferative diabetic retinopathy, macular oedema, vitreous haemorrhage, or need for retinopathy-related treatment, assessed over 10 years. Risk ratios (RR) and hazard ratios (HR) with 95% confidence intervals (CI) were reported. RESULTS: Among 130,002 patients with NPDR, Hispanic (RR 1.40, 95% CI 1.32-1.48), Black (RR 1.15, 95% CI 1.10-1.20), and Other (RR 1.13, 95% CI 1.04-1.24) patients demonstrated higher risks of TW-DED progression than White patients. In multivariable analysis, race/ethnicity was no longer significant, whereas DFU (HR 1.08, 95% CI 1.02-1.15) and DN (HR 1.06, 95% CI 1.01-1.12) remained independently associated with TW-DED. Stratified analysis revealed DFU consistently conferred greater risk than DN (Hispanic HR 1.39; Other HR 1.32; Black HR 1.27; White HR 1.22). CONCLUSION: Hispanic, Black, and Other groups had higher risk of TW-DED progression, but differences diminished after comorbidity adjustment. DFU and DN independently predicted progression, with DFU posing greater risk, suggesting microvascular disease burden and management differences may underlie racial differences.