In terms of genetic overlap, individual loci such as INS, TH, CTRB1, CENPW, HLA-DRA [15], GLIS3 [16], MTNR1B, HNF1A [17], and POU5F1-TCF19 [15] been reported to be associated with both T1D and T2D in large-scale GWAS. This evidence concerns the gene HNF1A and type 1 diabetes mellitus.