Evidence Suggesting the Role of Gut Dysbiosis in Diabetic Retinopathy

PURPOSE: Gut dysbiosis has been identified and tested in human trials for its role in diabetes mellitus (DM). The gut–retina axis could be a potential target for retardation of diabetic retinopathy (DR), a known complication of DM. This study reviews the evidence suggesting gut dysbiosis in DR. METHODS: The published literature in the past 5 years was reviewed using predetermined keywords and articles. The review intended to determine changes in gut microbiome in DR, the hypothesized mechanisms linking to the gut–retina axis, its predictive potential for progression of DR, and the possible therapeutic targets. RESULTS: The gut microbiota of people with DM differ from those without it, and the gut microbiota of people with DR differ from those without it. The difference is more significant in the former (DM versus no DM) and less significant in the latter (DM without DR versus DM with DR). Early research has suggested mechanisms of the gut–retina axis, but these are not different from known changes in the gut microbiome of people with DM. The current evidence on the predictive value of the gut microbiome in the occurrence and progression of DR is low. Therapeutic avenues targeting the gut–retina axis include lifestyle changes, pharmacologic inhibitors, probiotics, and fecal microbiota transplantation. CONCLUSIONS: Investigating the therapeutic utility of the gut ecosystem for DM and its complications like DR is an emerging area of research. The gut–retina axis could be a target for retardation of DR but needs longitudinal regional studies adjusting for dietary habits.