Could Vitamin D be Associated with Proliferative Diabetic Retinopathy? Evidence from Pooling Studies

Contrasting data about the association between proliferative diabetic retinopathy (PDR) and vitamin D status remain unknown. First, a hospital-based cross-sectional study consisting of 889 diabetic retinopathy (DR) and non-DR (NDR) patients was admitted. Further the accumulated evidence was performed to explore the association and dose-response relationship. Our study indicated that the odd ratio for PDR in vitamin D deficiency (VDD) individuals was significantly increased (1.60, 95% CI 1.06-2.42), compared with NDR in vitamin D sufficiency individuals, adjusted by age, sex, diabetic duration, and HbA1c. Four studies plus our study with data on vitamin D levels in 4970 patients with PDR and NDR subjects are compared. Association between vitamin D deficiency and risk of PDR exists (OR=1.69, 95% CI 1.40-2.05; I²=0%, p=0.61). Association between a nonlinear trend for vitamin D decrease with risk of DR was significant (chi²=16.53, p=0.0003). No significant heterogeneity in identified studies was found (goodness of fit chi²=2.98, p=0.225). It is concluded that vitamin D deficiency is significantly associated with risk of proliferative diabetic retinopathy.