Vitamin D Deficiency as a Risk Factor for Diabetes and Poor Glycemic Control in Saudi Arabia: A Systematic Review.

This systematic review aims to investigate the published literature on vitamin D deficiency (VDD) as a risk factor for developing type 2 diabetes mellitus (T2DM) or affecting the glycemic state of patients in Saudi Arabia. PubMed, Scopus, Web of Science, ScienceDirect, and the Cochrane Library were systematically searched to include the relevant literature. Rayyan QCRI (Rayyan Systems Inc., Cambridge, MA) was used throughout this systematic approach. Eleven studies were included with a total of 4229 patients. Three studies demonstrated that VDD was a significant risk factor for developing T2DM, and one reported that it increased insulin resistance. However, two studies found that VDD did not affect the incidence of T2DM and did not affect the insulin sensitivity or glycated hemoglobin (HbA1c) levels in patients with T2DM. This systematic review demonstrated that VDD significantly increases the risk of developing T2DM and negatively affects the glycemic state of patients with T2DM among Saudi patients. Due to the many populations examined, vitamin D chemical compositions, doses, and supplementation periods, interventional research has produced contradictory and ambiguous results. Additional research is necessary, particularly in individuals with a high risk of developing diabetes (impaired fasting glucose and/or glucose tolerance, possibly without obesity). These individuals may be the primary benefactors of vitamin D's benefits in preventing T2DM, according to the hypothesized mechanism of action for the vitamin.