Diabetic Retinopathy Predicts All-Cause Mortality and Cardiovascular Events in Both Type 1 and 2 Diabetes: Meta-analysis of observational studies

OBJECTIVE: The prognostic significance of diabetic retinopathy (DR) for death and cardiovascular (CV) outcomes is debated. We investigated the association of DR with all-cause mortality and CV events in patients with diabetes by a systematic review and meta-analysis. RESEARCH DESIGN AND METHODS: The electronic databases Medline and Embase were searched for cohort studies that evaluated DR in type 2 or type 1 diabetic patients and reported total mortality and/or fatal and nonfatal CV events, including myocardial infarction, angina pectoris, coronary artery bypass graft, ischemic changes on a conventional 12-lead electrocardiogram, transient ischemic attack, nonfatal stroke, or lower leg amputation. Data extraction was performed by two reviewers independently. Pooled effect estimates were obtained by using random-effects meta-analysis. RESULTS: The analysis included 20 studies that fulfilled the inclusion criteria, providing data from 19,234 patients. In patients with type 2 diabetes (n = 14,896), the presence of any degree of DR increased the chance for all-cause mortality and/or CV events by 2.34 (95% CI 1.96-2.80) compared with patients without DR. In patients with type 1 diabetes (n = 4,438), the corresponding odds ratio was 4.10 (1.50-11.18). These associations remained after adjusting for traditional CV risk factors. DR was also predictive of all-cause mortality in type 2 diabetes (odds ratio 2.41 [1.87-3.10]) and type 1 diabetes (3.65 [1.05-12.66]). CONCLUSIONS: The presence of DR was associated with an increased risk of all-cause mortality and CV events in both type 2 and type 1 diabetic patients.