Objective To explore the surface morphological and biomechanical properties differences of peripheral blood mononuclear cells (PBMCs) between groups of patients with mitochondrial diabetes caused by mt.3243A ＞ G mutation and healthy controls.Methods 2 milliliters blood were obtained from each subject of the mitochondrial diabetes group (n =5) and the control group (n =5).The PBMCs were separated from the blood using the standard Ficoll-Hypaque density-gradient centrifugation method and detected by atomic force microscope (AFM).Results The morphological analysis revealed that compared with control group,the PBMCs of diabetic patients tended to have a lower cell height (0.73 ± 0.24μm vs 2.49 ± 1.17μm,P =0.011) and a much rougher cell membrane (Ra:161.8 ± 33.2nm vs 66.4 ± 16.3 nm,P =0.000;Rq:202.2 ± 40.9nm vs 85.4 ± 17.1 nm,P =0.000).The adhesion force distribution was nearly three times higher in PBMCs of diabetic patients than that of the control group (779.6 ± 190.0pN vs 161.1 ± 83.1 pN,P =0.000).The Young's modulus of PBMCs was significantly increased in diabetic patients (421.4 ± 140.0kPa vs 138.3 ± 77.2kPa,P ＜ 0.01),indicating that diabetic PBMCs were stiffer than control cells.Conclusion Our study demonstrated the surface morphological and biomechanical properties changes in mitochondrial diabetes caused by mt.3243A ＞ G mutation at PBMCs level,which was beneficial to the better understanding of the pathophysiological mechanisms of mitochondrial diabetes associated with mt.3243A ＞ G mutation.