Association of serum vitamin D levels and diabetic retinopathy in Asian Indians with type 2 diabetes

Background: Vitamin D deficiency (VDD) is a condition that has been associated with diabetic retinopathy (DR) in various populations, but has not been studied in Asian Indians. Aims: To evaluate the association of serum 25-hydroxyvitamin D (25(OH)D) levels with presence and severity of DR among Asian Indians with type 2 diabetes. Methods: We collected information on individuals with type 2 diabetes that received care at a tertiary diabetes centre in India, between 2012 and 2015. Patients were 18 years of age or older, underwent retinal examinations with DR severity grading and had serum 25(OH)D measurements. Results: Serum 25(OH)D levels were lower in patients with retinopathy compared to those without (11.9 +/- 2.2 ng/ml vs. 13.7 +/- 2.1 ng/ml, p < 0.001). Stratifying patients by DR grade, reduced geometric means of 25(OH)D levels were associated with increased retinopathy severity. After adjusting for six key covariates, VDD was associated with increased rates of proliferative DR (OR 2.05; 95% CI 1.35-3.11; p = 0.001). Conclusions: In Asian Indians with type 2 diabetes, lower serum 25(OH)D was associated with increased severity of DR and the presence of VDD was associated with a two-fold increased risk for proliferative DR. (C) 2018 Elsevier B.V. All rights reserved.