TCF7L2 and type 2 diabetes mellitus: Our results first indicate that the β-cell function (HOMA2-B) increase observed in the TCF7L2 rs7903146 “CC” homozygotes as part of an adequate adaptation process becomes disrupted in “T” risk allele carriers and this difference develops to be higher along with the increase of PTGC early during the course of T2DM development.