Abstract: Although the etiology and pathogenesis of type 2 diabetes mellitus(T2MD) have not been fully illuminated,but the relevant knowledge is gradually deepened with the concept being shifted from glucose and lipid metabolic disorders to immune and inflammatory mechanisms related to the occurrence of T2MD.In addition to its known roles in calcium and phosphorus metabolism and the skeleton formation,vitamin D has been reported to have multiple biological effects due to the existence of vitamin D receptor in several cells and tissues.Of great interest in its functional aspects is that vitamin D can reduce the risk of some chronic illness,such as cancers,diabetes and cardiovascular disease.In this article,we summarize the role of vitamin D in β-cell function impairment,insulin resistance,and immune and inflammation regulation,emphasizing on functional mechanism of vitamin D in the occurrence and development of T2DM,and discuss the impact of vitamin D receptor polymorphism on disparities in intervention efficacy of vitamin D supplementation for T2DM prevention and treatment in human.