A systematic review and meta-analysis of research on vitamin D deficiencies and diabetic retinopathy has reported a statistically significant odds ratio of 1.44 (95% CI: 1.15 to 1.81, P=0.001) between deficiency in vitamin D and diabetic retinopathy (DR). The results of the systematic review were presented at the annual meeting of the American Association of Clinical Endocrinologists by Dr. Anawin Sanguankeo, MD, at the department of internal medicine, Bassett Medical Center, New York. While a full peer reviewed publication was not available at time of publishing this issue of EURETINA Brief, the finding may have clinically relevant implications if the results can be validated.
The researchers reviewed published studies indexed in the MEDLINE and EMBASE databases from their date of inception up to July 2015. The primary search uncovered 122 articles from which 13 studies were included, comprising a total of 9,350 participants with diabetes who had being assessed for both DR and vitamin D deficiency. According to the preliminary presented results, the pooled data showed a statistically significant association between DR and vitamin D deficiency. There was additionally a statistically significant lower serum 25-hydroxyvitamin D level in patient subgroups with DR compared to control groups with a mean difference of -2.25 ng/mL (95% CI: -3.64 to -0.87, P=0.001). A further uncertainty in the data revealed to date is how the research may apply to different populations in different regions of the globe. Vitamin D levels may vary depending on latitude and, as such, a sub-analysis investigating the association of latitude, vitamin D levels and DR may provide an additionally interesting field of inquiry.
In summary, if the full research study is published and validated it may support a simple clinical strategy of vitamin D supplementation, which according to the researchers, provide “a protective mechanism against the development and progression of DR, particularly in elderly female patients, warrants further investigation”. However, a significant body of clinical research would be required before such supplementation could be recommended as an efficacious intervention to manage diabetic retinopathy.