AHR and diabetes mellitus: Given that histone modifications involving H3K4me3 and H3K9Ac are associated with changes in gene expression relevant to diabetes—and that the AhR/CYP1 pathway also induces modifications of specific histones, such as H3K9Ac and H3K4me3—it is plausible that histone-mediated epigenetic regulation may serve as a mechanistic link between AhR/CYP1 activity and β-cell dysfunction in diabetes.