IRS1 and type 2 diabetes mellitus: Intravenous injection of hucMSC-ex reduced blood glucose levels. In T2DM, HucMSC-ex restored insulin receptor substrate 1 and protein kinase B phosphorylation (tyrosine site), increased muscle glucose transporter 4 expression, and increased liver glycogen storage to maintain glucose homeostasis by increasing glycogen storage. HucMSC-ex inhibits STZ-induced apoptosis, relieving T2DM of insulin-secreting functions