MAFA and Hyperglycemia: Ablation of Foxo1 in β cells causes hyperglycemia in multiparous or aged mice by downregulating expression of insulin and key β‐cell transcription factors, including the NK class of homeodomain‐encoding gene 6.1 (NKX6.1), pancreatic and duodenal homeobox 1 (PDX1), and MAF BZIP transcription factor A (MAFA) genes.