Association between diabetic retinopathy with serum vitamin D levels in patients with type 2 diabetes mellitus

Purpose: The role of Vitamin D(Vit D) in angiogenesis regulation, inhibition of inflammation and neovascularization has been proved in biological studies. Regarding the discrepancy among the results of previous studies searching about the relation between serum Vit D level and diabetic retinopathy, this study was conductd to further investigate this association. Methods: In this cross-sectional study, 164 patients with type 2 diabetes who had conditions for entering the study were selected. Patients were classified into three groups based on funduscopic eye examination; without diabetic retinopathy (16 subjects), diabetic nonproliferative retinopathy (42) and diabetic proliferative retinopathy (106). After testing FPG, HbA1c, 25 OH vitD, deficiency of vitamin D was defined as less than 30 ng / ml for serum levels of 25 OH vitD. The relationship between the severity of diabetic retinopathy and serum vitamin D levels was investigated. Results: Results: The samples were 164 (60.4% female) with a mean age of 61.84 ± 8.52. The prevalence of diabetic retinopathy was 90.2%. 25.6% of them had non-proliferative diabetic retinopathy and 64.6% had proliferative diabetic retinopathy. The results of multiple ordinal analysis showed that variables like FPG with odds ratio (0.99), HbA1c with odds ratio (2.68) had a significant relationship with diabetic retinopathy. Also after adjusting the variables such as age, sex, duration of diabetes, hypertension, FPG and HbA1c, serum vitamin D levels with odds ratio (2.24) and P = 0.045 had a significant effect on the severity of diabetic retinopathy. Conclusion: The result of this study showed that there is a relationship between the severity of diabetic retinopathy and serum vitamin D levels.