Downregulation of FOXO1 may be caused by chronic hyperglycemia‐induced oxidative stress; consequently, β‐cell fate cannot be maintained, due to insufficient β‐cell transcription factors, PDX1, MAFA, and NKX6.1, all of which are FOXO1‐dependent (Kitamura et al., 2005). This evidence concerns the gene MAFA and Hyperglycemia.