Abstract

The gut microbiome can play a pivotal role in the pathogenesis of diabetic retinopathy (DR). This study aimed to synthesize the evidence regarding the relationship between the dysbiosis of the gut bacterial microbiome and DR. A systematic search was conducted across several databases. The outcomes included alpha diversity and/or relative abundance of the gut bacterial microbiome. The results were pooled and presented as the standardized mean difference with 95% confidence intervals. Nine studies were included. The reported indices of alpha diversity were quantitatively pooled using a random effects model, as significant heterogeneity was detected. There was no significant difference between the DR and DM in any of the pooled indices (all p-values >0.05). In addition, pooling of relative abundance was conducted using a random-effects model for all phyla, as significant heterogeneity was detected. There was no significant difference between the DR and DM in any of the pooled estimates (all p-values >0.05). The current meta-analysis revealed a lack of significant differences in alpha diversity indices between diabetic patients with and without DR. This lack of significance was observed not only across all measured indices of alpha diversity but also at the level of major bacterial phyla.

Key words: Diabetes mellitus, diabetic retinopathy, dysbiosis, gastrointestinal microbiome, gut-retina axis, meta-analysis