Association of non-alcoholic fatty liver disease with diabetic retinopathy in type 2 diabetic patients: A meta-analysis of observational studies

Aims/Introduction: Non-alcoholic fatty liver disease (NAFLD) is becoming more and more prevalent in type 2 diabetes mellitus. Evidence connecting NAFLD to diabetic retinopathy (DR) is increasing, but the results vary. Thus, we undertook a meta-analysis to explore the effect of NAFLD on diabetic retinopathy in patients with type 2 diabetes mellitus. Materials and Methods: PubMed, Embase, Cochrane and Scopus database were searched for until September 30, 2019. Original studies analyzing the association between NAFLD and diabetic retinopathy in the type 2 diabetic population were included. This meta-analysis was processed by RevMan 5.3 software. Subgroup analyses based on countries were carried out. The pooled odds ratios and 95% confidence intervals were used to evaluate the association between NAFLD and diabetic retinopathy incidence. The I-2 test was used to assess heterogeneity of studies. Results: We retrieved 414 articles, and nine studies involving 7,170 patients were included in the final analysis. The pooled effects estimate suggested that NAFLD was not associated with the risk of diabetic retinopathy in patients with type 2 diabetes mellitus. Subgroup analysis suggested that in China, Korea and Iran, patients with type 2 diabetes mellitus with NAFLD had a decreased risk for diabetic retinopathy compared with the non-NAFLD individuals. However, in Italy and India, patients with type 2 diabetes mellitus with NAFLD had an increased risk for diabetic retinopathy compared with the non-NAFLD individuals. In addition, no relevance between NAFLD and diabetic retinopathy was found in America. Conclusions: On the whole, there was no association between NAFLD and diabetic retinopathy in individuals with type 2 diabetes mellitus. However, subgroup analysis showed that a difference of country may have an influence on the result.