Of these loci, only GCK, MTNR1B, DGKB, GCKR, ADCY5 and PROX1 (besides TCF7L2 and SLC30A8) were associated with type 2 diabetes at genome-wide significance levels, with several others (but not all) showing a consistent trend but not meeting the same stringent statistical threshold. Here, TCF7L2 is linked to type 2 diabetes mellitus.