The global prevalence of type 2 diabetes mellitus (T2DM) has increased, as well as complications including diabetic retinopathy. Polymorphisms in transcription factor 7-like 2 (TCF7L2) have been associated with T2DM, with the strongest association attributed to the single-nucleotide polymorphism rs7903146. In this review, we searched the current literature to determine whether an association exists between TCF7L2 polymorphisms rs7903146 with diabetic retinopathy.
Vitamin D deficiency and insufficiency are increasingly being recognized in the general population over the last few decades. However, a number of other disorders have now been linked to vitamin D deficiency and insufficiency, including asthma and COPD. The aim of this study was to evaluate the evidence on the effect of vitamin D on asthma and COPD. We searched electronic databases including SCI, EMBASE, Ovid, and PubMed. Reviewers working independently and in duplicate extracted study characteristics, quality, and the outcomes.