ER stress is considered one of the underlying causes of T2DM[50], and a large number of studies have proved that the long-term enhanced ER stress causes cell apoptosis and leads to dysfunction of the islet cell by reducing the expression of key transcription factors like PDX1 and MAFA, which are involved in regulating insulin transcription[51–54]. This evidence concerns the gene MAFA and type 2 diabetes mellitus.