FOXO1 and type 2 diabetes mellitus: In contrast to these apparent salubrious effects of FoxO TFs, FoxO1 can contribute to metabolic dysregulation similar to that observed in Type 2 diabetes, as FoxO1 haploinsufficiency protects mice against insulin resistance induced by a high-fat diet [17], and both liver-specific and osteoblast-specific FoxO1 deletion ameliorate glucose intolerance in mouse models of insulin resistance [18,19,20].