IRS1 and type 2 diabetes mellitus: Similarly, in the longitudinal study of 1,144 Puerto Ricans of the BPRHS discussed above (159), a significant interaction between vitamin D status and IRS1 rs2943641 on the risk of T2D was identified in women in which minor allele homozygotes (“TT”) had a lower risk of T2D compared with “C” allele carriers only when 25(OH)D was higher than the median [>17 ng/mL (42.4 nmol/L)] (Pinteraction = 0.007), but the interaction was not observed in men.