The newly discovered role of Vitamin D is now the current area of research as the ubiquitous presence of its receptor VDR and the presence of its activating enzymes like 1 alpha Hydroxylase implies its effect in various other metabolic processes other than bone growth and calcium metabolism. This review articles discusses about the role of Vitamin D deficiency and beneficial effect of its replenishment in Diabetes Mellitus particularly at molecular level affecting gene expression through various pathways. This new fangled role of Vitamin D in Diabetes Mellitus opens a new arena of research and prevention of Diabetes mellitus by its supplementation therapy.