Redox Biomarker Alterations and Disrupted Uric Acid–Catalase Activity Association in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is characterized by metabolic disturbances in which oxidative stress may play an important role. Most existing studies have examined individual biomarkers rather than their interrelationships. The present study evaluated selected oxidative stress, metabolic, and antioxidant markers, as well as their associations, in women with GDM compared with healthy pregnant controls. A total of 160 pregnant women (87 with GDM and 73 controls) were included. Biomarkers were measured, and their associations were assessed using correlation and interaction analyses. Women with GDM demonstrated higher levels of malondialdehyde (p < 0.001), leptin (p = 0.007), and ferric reducing antioxidant power (p < 0.001). The difference in the correlation between catalase activity and uric acid remained statistically significant after false discovery rate correction (q = 0.006), with a negative association in women with GDM and a positive association in controls. Interaction analysis further supported a group-dependent relationship between uric acid and catalase activity (p = 0.007; FDR-adjusted q = 0.007). These findings suggest that GDM may be associated not only with changes in individual biomarkers but also with alterations in selected redox-related relationships, indicating differences in redox regulation in GDM.