Diabetic retinopathy and dementia risk: A systematic review and meta-analysis

Diabetic retinopathy (DR) is associated with elevated dementia risk. However, no previous studies have quantified the strength or impact of this association. To address this, our study explored the relationship between DR and dementia. We searched Web of Science, Scopus, and PubMed for observational studies between January 1, 2000, and May 1, 2024, examining data showing an association between DR and dementia. No filters were used in these searches. Eligibility restrictions, including limitations in observational study designs and publications in English, were applied as pre-specified post-search screening steps. Pooled relative risk (RR) and 95% confidence intervals were estimated using the DerSimonian-Laird random-effects model. Nine observational studies including 2,887,409 patients were included. DR correlated with a significantly higher risk of all-cause dementia despite high inter-study heterogeneity. DR also correlated with an elevated risk of Alzheimer's disease, although this effect estimate and associated heterogeneity were dominated by a single large Korean cohort study and should be interpreted cautiously. The trim-and-fill-adjusted estimate suggested some overestimation of the primary pooled RR. No significant association with vascular dementia was found. Egger's test evaluated potential publication bias. The overall findings suggest a positive relationship between DR and dementia risk, specifically for all-cause dementia, although the evidence is limited by high heterogeneity, meaningful publication bias, and an observational study design that precludes causal inference. DR may indicate a clinical need for heightened cognitive surveillance in patients with diabetes. Future prospective studies with standardized dementia ascertainment and greater ethnic diversity are required to confirm these findings. PROTOCOL REGISTRATION: International Platform of Registered Systematic Review and Meta-analysis Protocols INPLASY202620035; https://doi.org/10.37766/inplasy2026.2.0035.