CD81 and type 2 diabetes mellitus: Western blot analysis revealed that the protein expression of small EV markers (Alix, CD81, CD63) was significantly increased in DN patients (Fig. 1B), indicating that a greater number of small EVs were secreted in urine of DN patients compared with T2DM patients and healthy controls (HC), which was confirmed by particle quantification through nanoparticle tracking analysis (Fig. 1C).