We found that the AlbCre;Xbp1flx/flx mice displayed significantly impaired fasting glycemia, hyperinsulinemia, and impaired glucose tolerance by 50–60 weeks of age (Fig. 1g, h), suggesting that hepatic loss of Xbp1 led to a state of metabolic dysregulation similar to that observed in human NAFLD. Here, XBP1 is linked to hyperinsulinism.