TXNDC5 and Hyperglycemia: Sustained hyperglycaemia damages β cell function through several ways such as the increase of oxidative stress, activation of JNK pathway through activated p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase C (PKC), the reduction of the pancreatic and duodenal homeobox factor-1 (PDX-1) function, and the reduction of ERp46 expression [17–19].