We aimed in the current research to study the frequency of SNPs in VitD interrelated genes, mainly rs1155563 in GC, rs12785878 in DHCR7 and rs10500804 in CYP2R1 and their link with measures of glycaemia (insulin sensitivity indices, fasting insulin, blood sugar and c-peptide) in females diagnosed with T2DM in Kingdom of Saudi Arabia. The gene discussed is CYP2R1; the disease is type 2 diabetes mellitus.