Background <p>Gestational diabetes (GDM) is the most common pregnancy-related metabolic disorder and a major risk factor for both mother and a child, during pregnancy and after delivery. Impairment of the anti-oxidative system acts as the driving force of the devastating consequences in GDM, while microRNA molecules are affected by disturbances related to (glyco)oxidative stress ((g)OS) and emerged as potential sensors and effectors of (g)OS-associated mechanisms. Aims: The aim of the present study was to evaluate the potential of OS-related microRNAs miR-27a, miR-222 and miR-340 from peripheral blood mononuclear cells (PBMCs) to serve as OS indicators of in GDM.</p> Methods and results <p>MicroRNA quantification was conducted in samples of patients with GDM and normoglycemic controls (<i>n</i> = 45 each). Levels of expression were tested for correlations with the activities of glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) and serum thiol content. MiR-27a demonstrated correlation with the expression of other two microRNAs. GR activity during pregnancy weeks 24–28 was increased in GDM, while thiol content showed an opposite direction of change. Similar results were acquired when comparing GDM patients with and without adverse pregnancy outcomes. The expression of tested microRNAs was positively correlated with the activity of GR in GDM group, while the correlation of the expression of miR-27a-3p and miR-340-5p with SOD activity and blood thiol content was negative.</p> Conclusions <p>Our findings support the relevance of redox dysregulation in mid-pregnancy for developing obstetric and neonatal complications. The results also qualify miR-27a-3p, miR-222-3p and miR-340-5p for redox status indicators in GDM.</p>