Relationship between Proliferative Diabetic Retinopathy and Inflammatory Markers in Patients with Type 1 Diabetes in Brazil: A Nested Case Control Study

Introduction: This study examined the relationship between proliferative diabetic retinopathy (PDR) and serum levels of C-reactive protein, VEGF, TNF-α, and IL-6 inflammatory biomarkers, related to the pathophysiology of diabetic retinopathy. Methods: This cross-sectional, case control study comprised 240 patients with type 1 diabetes (80 cases with PDR and 160 controls without diabetic retinopathy) who were matched for gender and duration of diabetes. Results: C-reactive protein was the only inflammatory biomarker that was positively related to PDR (OR 1.96; 95% CI 1.01–3.78, p = 0.0045). We also noted an association between high glycated hemoglobin levels, the use of angiotensin-converting enzyme inhibitor, low glomerular filtration rate, and PDR. Conclusion: Patients with higher levels of C-reactive protein are more likely to present with PDR. We did not find a link between serum levels of VEGF, TNF-α, or IL-6 and PDR. The function of inflammatory biomarkers in PDR must be addressed in further studies.