ARNT (Aryl Hydrocarbon Receptor Nuclear Translocator), also known as HIF1β (hypoxia inducible factor-1β), is a heterodimer of the basic helix-loop-helix (bHLH-PAS) family of transcription factors including HIF1α, HIF2α, and AhR. ARNT is positioned on human chromosome 1q21–q24, and research has revealed that this region has presented a well replicated linkage to T2DM; alteration in the ARNT gene increases the risk of T2DM by impaired insulin secretion [46]. The gene discussed is AHR; the disease is type 2 diabetes mellitus.