TCF7L2 and type 2 diabetes mellitus: Interestingly, we also found that diabetes-associated genetic variants overlap with open chromatin of GLIS3 as well as of several other candidate genes for type 2 diabetes genes such as TCF7L2 and KCNQ1 [73] and based on the strong interaction between genetic variation and DNA methylation, and the potential impact of non-genetic factors [74–76], we chose not to filter our CpG-SNPs in the present study.