INS and type 2 diabetes mellitus: The review systematically elaborates on the key roles of exosomes from different cell sources in regulating T2DM and its complications, focusing on how these exosomes, through their specific microRNAs (miRNAs), proteins, and other active substances they carry, act on different key targets and thereby regulate core pathological processes such as insulin signaling pathways, inflammatory responses, cell apoptosis, fibrosis, and angiogenesis.