Interestingly, a more recent Chinese MR study [51] on 2393 participants (361 cases with T2D) showed a marginal protective effect of higher 25OHD levels on T2D risk using two vitamin D synthesis SNPs in CYP2R1 and DHCR7, but no effect when using four SNPs in both synthesis and metabolism genes (CYP2R1, DHCR7, GC, and CYP24A1). Here, CYP2R1 is linked to type 2 diabetes mellitus.