TCF7L2 and diabetes mellitus: Although deletion of TCF7L2 selectively in the pancreas (50) or β-cell (51) in mice lowers β-cell function, increased levels of TCF7L2 mRNA are associated with elevated diabetes risk in man (52, 53), with the latter study reporting increased levels of the 3’ exon (and 15 o 18 exons overall) in islets of carriers of the risk rs7903146 allele.