Some previous studies have reported inconsistent results on the association between alcohol intake and diabetic retinopathy (DR) risk. This study aimed to evaluate the potential effects of alcohol intake on subsequent DR risk using a meta-analytic approach.
Three electronic databases (PubMed, EmBase, and the Cochrane library) were systematically searched for observational studies from their inception till November 2019. The pooled odds ratio (OR) with 95% confidence interval (CI) were applied for the summary effect estimate using a random-effects model.
A total of 15 studies (5 cohort studies, 4 case-control studies, and 6 cross-sectional studies) with 37,290 participants and 12,711 DR cases were selected for the final meta-analysis. The pooled OR indicated no significant association between alcohol intake and DR risk (OR: 0.91; 95%CI: 0.78-1.06; P = 0.225), irrespective of the studies being pooled cohort (OR: 0.95; 95%CI: 0.66-1.36; P = 0.761), case-control (OR: 0.97; 95%CI: 0.77-1.23; P = 0.818), or cross-sectional (OR: 0.86; 95%CI: 0.69-1.08; P = 0.190) ones. However, this association might have been affected by the type of diabetes mellitus and the adjusted status.
The results of this study showed that the potential impact of alcohol intake on DR risk may differ according to the type of diabetes mellitus and adjusted status. Further large-scale, prospective cohort studies should be conducted to verify the findings of this study and to evaluate DR risk in relation to the dose and type of alcohol intake.

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