Proteinuria in early referral to spectral domain optical coherence tomography for macular edema detection in type 2 diabetes individuals: results from the Brazilian diabetes study

Background Measurement of retinal thickness by optical coherence tomography (OCT) shows higher diagnostic accuracy for diabetic macular edema (DME) than fundus photography alone. The expanding gap between the rising number of type 2 diabetes (T2D) individuals and the availability of OCT devices demands a targeted selection of individuals at higher risk of DME who would benefit the most from early referral. We sought to appraise if proteinuria should be considered in a targeted referral of T2D individuals to OCT examination. Methods This study was a cross-sectional analysis of 576 consecutive patients enrolled in the Brazilian Diabetes Study between June/2016 and December/2021 who underwent OCT exam and urinalysis to assess ME and proteinuria status, respectively. Differences in the prevalence of DME between proteinuria groups and across a range of diabetic retinopathy (DR) stages were evaluated. Results Among 1134 eyes included in this analysis, the prevalence of proteinuria was 22% and 18.2% of eyes had DME. Proteinuria was related to an increased prevalence of DME (13.2% vs 38.7% for control vs proteinuria, respectively; p < .001), with an OR of 4.08 [95% confidence interval (CI): 2.50-6.64, p < .001), after adjustment for covariates. Proteinuria was independently related to DME also among eyes with non-apparent DR [OR: 2.82; 95%CI: 1.34-5.93; p = .003] and non-proliferative DR (OR of 5.94, 95%CI 2.13-16.62, p < .001). Fundus photography spotted only half of the DME cases detected by OCT. Conclusion In T2D individuals, early referral to OCT examination should be pursued for all individuals with concurrent proteinuria.