Oxidative lipid, protein, and DNA damage as oxidative stress markers in vascular complications of diabetes mellitus

Purpose: The purpose of this study was to determine the effects of diabetic complications on oxidation of proteins, lipids, and DNA and to investigate the relationship between oxidative damage markers and clinical parameters. Methods: The study group consisted of 69 type 2 diabetic patients (20 patients without complication, 49 patients with complication) who attended internal medicine outpatient clinics of Istanbul Education and Research Hospital and 19 healthy control subjects. In serum samples of both diabetic patients and healthy subjects, 8-hydroxy-2'deoxyguanosine (8-OHdG), as a marker of oxidative DNA damage, N-epsilon-(hexanoyl)lysine (HEL) and 15-F2t-iso-prostaglandin (15-F2t-IsoP). as products of lipooxidative damage, advanced oxidation protein products (AOPP), as markers of protein damage, and paraoxonase1 (PON1) as antioxidant were studied. Results: 15-F2t-IsoP (p<0.005) and AOPP (p<0.001) levels were significantly higher in diabetic group than control group while there were no significant differences in levels of 8-OHdG and HEL between the two groups. AOPP (p<0.001) and 8-OHdG (p<0.001) were significantly higher in diabetic group with complications compared to diabetic group without complications. Conclusions: Increased formation of free radicals and oxidative stress, under conditions of hyperglycaemia, is one of the probable causes for evolution of complications in diabetes mellitus. Our study supports the hypothesis that oxidant/antioxidant balance is disturbed in diabetic patients.