Association between the Angiotensin-Converting Enzyme (ACE) Genetic Polymorphism and Diabetic Retinopathy—A Meta-Analysis Comprising 10,168 Subjects

Aims—to address the inconclusive findings of the association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism on risk of diabetic retinopathy (DR), a meta-analysis was conducted. Methods—we conducted a meta-analysis on 4252 DR cases and 5916 controls from 40 published studies by searching electronic databases and reference lists of relevant articles. A random-effects or fixed-effects model was used to estimate the overall and stratification effect sizes on ACE I/D polymorphism on the risk of DR. Results—we found a significant association between the ACE I/D polymorphism and the risk of DR for all genetic model (ID vs. II: OR = 1.14, 95% CI: 1.00–1.30; DD vs. II: OR = 1.38, 95% CI: 1.11–1.71; Allele contrast: OR = 1.17, 95% CI: 1.05–1.30; recessive model: OR = 1.24, 95% CI: 1.02–1.51 and dominant model: OR = 1.21, 95% CI: 1.06–1.38, respectively). In stratified analysis by ethnicity and DM type, we further found that the Asian group with T2DM showed a significant association for all genetic models (ID vs. II: OR = 1.14, 95% CI: 1.01–1.30; DD vs. II: OR = 1.54, 95% CI: 1.14–2.08; Allele contrast: OR = 1.26, 95% CI: 1.09–1.47; recessive model: OR = 1.42, 95% CI: 1.07–1.88 and dominant model: OR = 1.26, 95% CI: 1.07–1.49, respectively). Conclusion—our study suggested that the ACE I/D polymorphism may contribute to DR development, especially in the Asian group with type 2 diabetes mellitus (T2DM). Prospective and more genome-wide association studies (GWAS) are needed to clarify the real role of the ACE gene in determining susceptibility to DR.