Aim. Fruits and vegetables are sources of phytonutrients that have a beneficial effect on human health [1]. A diet high in fruit and vegetables can help to protect an organism against diabetes mellitus (DM), heart disease, cancer and others. In particular, cornelian cherry fruits contain a diverse range of biologically active substances, and medicines based on them are promising for correction of disorders at various pathologies [2]. Therefore, the aim of the study was to investigate the effect of extracts from the “Uholok” and “Koralovyi” cultivars of C. mas and the hybrid C. mas. × C. officinalis fruits on plasma biomarkers of oxidative stress in diabetic rats. Conclusions. The extracts from the “Uholok” and “Koralovyi” cultivars of C. mas and the hybrid C. mas × C. officinalis fruits show strong antioxidant activity by preventing free radical oxidation of plasma biomacromolecules under DM. These extracts have the potential to be developed into antidiabetic drugs.