INTRODUCTION: Diabetes is associated with increased lipid peroxidation, quantified as the levels of thiobarbituric acid reactive substances (TBARS). In parallel, the antioxidant defense system (ADS) reacts to diminish the oxidative damage. OBJECTIVE: To determine the levels of lipid peroxidation and the activity of antioxidant enzymes in obese type 2 diabetic (DM2) individuals compared to non-obese DM2 individuals. METHODS: Lipid peroxidation was quantified by measuring TBARS and the ADS response by measuring the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). RESULTS: Two groups of 30 subjects were studied. The obese DM2 group had a mean body mass index (BMI) 38.6 ± 3.5 kg m(-2) compared to the control group 24.7 ± 3.6 kg m(-2) (p