PAX6 and diabetes mellitus: Importantly for the concept of metabolic regulation of beta cell identity, many of the transcription factors mentioned above, specifically Pdx1, Nkx6.1, MafA and Pax6, as well as Foxo1, are inactivated by hyperglycemia (Jonas et al., 1999; Talchai et al., 2012; Guo et al., 2013; Brereton et al., 2014; Wang et al., 2014; Cinti et al., 2016), providing a plausible mechanism for compromised beta cell identity in diabetes.