Association Between Vitamin D Deficiency and the Risk of Diabetic Retinopathy in Patients With Type 2 Diabetes: A Meta-Analysis.

BACKGROUND

Diabetic retinopathy (DR) is a common microvascular complication of type 2 diabetes mellitus (T2DM) and a leading cause of blindness worldwide. Recent evidence suggests a potential role of vitamin D deficiency in the development of DR.

OBJECTIVE

To systematically evaluate the association between vitamin D deficiency and DR risk in T2DM patients through a meta-analysis of observational studies.

METHODS

A systematic literature search was conducted across major databases up to December 2024. Observational studies assessing serum 25(OH)D levels and DR risk were included. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed- or random-effects models depending on heterogeneity. Subgroup analyses, sensitivity analyses, and publication bias assessments were performed.

RESULTS

Twenty studies encompassing 22,408 T2DM patients were included. Vitamin D deficiency was significantly associated with increased DR risk (pooled OR = 1.17, 95% CI: 1.08-1.27, p < 0.001). Heterogeneity was moderate (I2 = 52%). Subgroup and sensitivity analyses confirmed robustness. No significant publication bias was observed.

CONCLUSION

Vitamin D deficiency (25[OH]D < 20 ng/mL) is associated with increased DR risk. Monitoring and correcting vitamin D status may aid in DR prevention. Future studies are needed to determine causality and evaluate the benefits of supplementation.