FIGURE1: mechanism of vitamin D action on pancreas (1) Alpha hydroxylase enzyme converts Vitamin D[25(OH) D3] to active Vitamin D [1, 25(OH)2 D3] inside the pancreatic Beta cell. (2)Vitamin D increases the transcriptional activation of the human insulin gene1.(3) Increased levels of insulin inside the beta cell. (4)Vitamin D promotes glucose mediated insulin secretion from the beta cell.2(5)Vitamin D ensures normal levels of extracellular calcium.3(6)Normal levels of extracellular levels of calcium ensures normal secretion of the insulin from the beta cells4. 1)Maestro B, Davila N, Carranza MC, Calle C. Identification of a Vitamin D response element in the human insulin receptor gene promoter. J Steroid BiochemMolBiol 2003;84:223-230. [PubMed: 12711007]] 2). Chertow BS, Sivitz WI, Baranetsky NG, Clark SA, Waite A, Deluca HF. Cellular mechanisms of insulin release: the effects of vitamin D deficiency and repletion on rat insulin secretion. Endocrinology 1983;113:1511-1518. [PubMed: 6352248] 102. Clark SA, Stumpf WE, 3.)Sar M. Effect of 1,25dihydroxyvitamin D3 on insulin secretion. Diabetes 1981;30:382-386. [PubMed: 7014306]] [.Sooy K, Schermerhorn T, Noda M, Surana M, Rhoten WB, Meyer M, Fleischer N, Sharp GW, Christakos S. Calbindin-D(28k) controls [Ca(2+)](i) and insulin release. Evidence obtained from calbindin-d(28k) knockout mice and beta cell lines. J BiolChem 1999;274:34343-34349. [PubMed: 10567411]] 4. )Beaulieu C, Kestekian R, Havrankova J, Gascon-Barre M. Calcium is essential in normalizing intolerance to glucose that accompanies vitamin D depletion in vivo. Diabetes 1993;42:35-43. [PubMed: 8380563]]