en Clinical Biochemistry Clinical Biochemistry Original Article Original Article <p style="text-align: justify;"><span style="font-size:12px;"><span style="font-family:Tahoma;"><span style="line-height:14.0pt">Type 2 diabetes mellitus (T2DM) is accompanied by oxidative stress, but few studies have examined lipid peroxidation, erythrocyte superoxide dismutase (SOD) activity, and SOD1/SOD2 mRNA expression together. In this cross-sectional case&ndash;control study, serum malondialdehyde (MDA) was measured using a TBARS assay, erythrocyte SOD activity by pyrogallol autoxidation inhibition, and peripheral blood mononuclear cell SOD1 and SOD2 mRNA expression by RT-qPCR. The primary analysis included 174 participants after eligibility review (114 with T2DM and 60 controls). Analyses of glycaemic tiers (n = 240), disease duration and treatment regimen (n = 120), and metabolic-syndrome strata (n = 235) were exploratory. All four markers differed between the T2DM and control groups (all p < 0.001). After adjustment for BMI and smoking, the T2DM group had higher MDA (adjusted ratio 3.02, 95% CI 2.55&ndash;3.57), lower erythrocyte SOD activity (0.64, 0.57&ndash;0.72), lower SOD1 mRNA expression (0.39, 0.30&ndash;0.49), and higher SOD2 mRNA expression (1.91, 1.55&ndash;2.37); all adjusted p < 0.001. Significant ordered trends were observed across glycaemic tiers and disease-duration tertiles. No treatment-regimen comparison remained significant after correction for multiple testing. Controls with and without metabolic syndrome did not differ on any marker. T2DM was associated with greater lipid peroxidation, reduced erythrocyte SOD activity, lower SOD1 mRNA expression, and higher SOD2 mRNA expression in peripheral blood mononuclear cells. The exploratory findings and case&ndash;control discrimination model require validation in independent cohorts.</span></span></span></p> Type 2 diabetes mellitus, Malondialdehyde, Superoxide dismutase, Oxidative stress, Glycaemic spectrum, Metabolic syndrome 1382 1395 http://ijmcmed.org/browse.php?a_code=A-10-9174-1&slc_lang=en&sid=1 Sama Al-Shaheeb Email: sama@mtu.edu.iq 100319475328460038285 100319475328460038285 Yes Institute of Medical Technology/Baghdad, Middle Technical University, Baghdad, Iraq Saleh Ali Alqadoori salehali@mtu.edu.iq 100319475328460038286 100319475328460038286 No Department of Medical Laboratory Techniques, Balad Technical Institute, Middle Technical University, Baghdad, Iraq Athir.K Mohammed athir.kadhim@mtu.edu.iq 100319475328460038287 100319475328460038287 No College of Health and Medical Techniques, Baghdad, Middle Technical University, Baghdad, Iraq