The oxidative stress in type 1 and type 2 diabetes mellitus (lipid peroxidation expressed as malondialdehyde concentration and antioxidative enzyme superoxide dismutase activity) was compared with parameters of diabetes control (glycated haemoglobin A1c and fructosamine concentrations) in the present study. Concentra- tions of malondialdehyde, glycated haemoglobin, fructosamine, glucose and superoxide dismutase activity were measured in a group of 45 type 1 diabetic patients (mean age 40±11 years, BMI 24.2±2.7 kg/m 2 ), 39 type 2 diabetic patients (mean age 56±11 years, BMI 28.4±4.3 kg/m 2 ) and in 20 healthy controls (mean age 34±10 years, BMI 24.3±1.9 kg/m 2 ). The total number of 150 examinations of fasting glucose, glycated haemoglobin and fructosamine was performed in 32 type 1 diabetic patients and 42 type 2 diabetic patients in attempt to compare diabetes control and the relationship between fructosamine and glycated haemoglobin. The malondialdehyde concentration was significantly higher in type 2 diabetic patients as compared to healthy controls (2.3±0.4 mmol/l and 1.89±0.18 mmol/l respectively, p<0.001), while no difference was found between type 1 diabetic patients (1.85±0.34 mmol/l) and the control group. A significant positive correlation was observed between malondialdehyde and body mass index (BMI) in type 2 diabetic patients (r = 0.394, p<0.02). A relationship was found between malondialdehyde and glycated haemoglobin in both types of diabetes (r = 0.4, p<0.01 in type 1, r = 0.46, p<0.04 in type 2 diabetes). Superoxide dismutase activity was slightly but nonsignificantly lower in type 1 (1.26±0.24 U) and type 2 (1.24±0.20 U) diabetes compared to healthy controls (1.31±0.13 U). Analysis of 150 examinations of fasting glucose, glycated haemoglobin and fructosamine revealed lower concentrations of fructosamine in type 1 diabetes than in type 2 (1.75±0.49 mmol/l and 2.02±0.46 mmol/l respectively, p<0.001) at similar concentrations of glycated haemoglobin. No difference was found in fasting glucose concentrations. Our results confirm the presence of increased oxidative stress predominantly in type 2 diabetes mellitus. These differences allow us to conclude that in type 2 diabetes the oxidative stress is more enhanced than in type 1 diabetes although diabetes control is comparable. This increase is probably caused by other factors

        Key words: diabetes mellitus, oxidative stress, malondialdehyde, superoxide dismutase, fructosamine.