STAT3 and type 2 diabetes mellitus: In islets from aged T2DM mice, miR‐21‐5p was decreased, IL‐6RA and pY705‐STAT3 were elevated, and PDX1/MCU were reduced; hAMSC‐sEVs partially reversed these abnormalities and restored MCU by immunoblotting and immunofluorescence (Figure S14a–d).