Aim. To date, there are limited and conflicting data regarding the effects of diabetic microenvironment on perinatal stem cells.Our study aims to assess impact of diabetes mellitus on functional responses of in vitro expanded WJ-MSCs derived from DM-mothers to oxidative stress. Methods. MSCs were obtained by the explant method and cultured according to standard methods. Oxidative stress was induced by hydrogen peroxide (H₂O₂) added as a pulse. Treated WJ-MSCs were analyzed for metabolic activity by MTT assay. Results. The dose-response effect of different concentration of H₂O₂ (6,25–440 µM) on WJ-MSCs derived from mothers with DM and healthy mothers was evaluated in vitro. The difference between diabetic and control groups in NOAEL values (no observed adverse effect level) was analyzed. Conclusions. The effect of oxidative stress on the metabolic activity in vitro of both normal and diabetic WJ-MSCs manifested according to the hormetic model of the response to the stressor (dose-response with stimulation by a low dose and inhibition by a high dose) and the threshold model with adaptation to low doses without stimulation. Although diabetic WJ-MSCs were more tolerant to moderate oxidative stress compared to the control cells according to NOAEL, there was no statistically significant difference in this parameter between groups according to the Mann-Whitney U test. Further studies on more amount of samples are needed to use this cell model for diagnostic applications and to develop criteria for donor cells.