Abstract
About one-third of individuals with diabetes develop diabetic retinopathy (DR), with one-tenth experiencing vision-threatening conditions such as diabetic macular edema (DME) or proliferative diabetic retinopathy (PDR). Current treatments only show recovery in 50% of cases, and the disease often remains asymptomatic. Therefore, novel early detection methods and new biomarkers are crucial. Our study aims to summarise evidence on the role of altered exosomal regulatory noncoding RNAs in DR, based on human studies. Observational studies delineating the different exosomal noncoding RNAs in DR were searched systematically from inception to June 2024 in PubMed-MEDLINE and SCOPUS databases. Preferred Reporting Items of Systematic Reviews and Meta-analysis (PRISMA) 2020 guidelines was used to conduct this systematic review (Prospero ID: CRD42023406724). We synthesised data from 13 human studies that assessed the expression of exosomal regulatory ncRNAs from individuals with DR. Among the 13 studies, nine focused on miRNA, while three examined lncRNA and one on circRNA. Although no common genes were identified across the studies, the review underscores the critical roles of exosomal noncoding RNAs in the pathogenesis of diabetic retinopathy, highlighting their potential as therapeutic targets. Future studies should aim for a unified approach in terms of sample selection, RNA analysis, and appropriate controls for a comprehension of exosomal expression patterns for early diagnosis of DR.