Type 2 diabetes mellitus (T2DM) is associated with endothelial dysfunction, which results in delayed wound healing. Mesenchymal stem cells (MSC) play a vital role in supporting endothelial cells (EC) and promoting wound healing via paracrine effects through their secretome-containing extracellular vesicles. We previously reported the impaired wound healing ability of adipose tissue-derived MSC from T2DM donors; however, whether extracellular vesicles isolated from T2DM adipose tissue-derived MSC (dEV) exhibit altered functions in comparison to those derived from healthy donors (nEV) is still unclear. In the present study, we found that nEV induced EC survival and angiogenesis, whereas dEV lost these abilities. In addition, under high glucose conditions, nEV protected EC from endothelial mesenchymal transition (EndMT), whereas dEV significantly induced EndMT by activating the TGF/Smad3 signaling pathway, which impaired the tube formation and in vivo wound healing abilities of EC. Interestingly, the treatment of dEV-internalized EC with nEV rescued the induced EndMT effects. Of note, the internalization of nEV into T2DM-derived adipose tissue-MSC resulted in the production of an altered n-dEV, which inhibited EndMT and supported the survival of T2DM db/db mice from severe wounds. Taken together, our findings suggest the role of dEV in endothelial dysfunction and delayed wound healing in T2DM by the promotion of EndMT. Moreover, nEV treatment can be considered as a promising candidate for cell-free therapy to protect EC in T2DM.