Oxidative DNA damage in peripheral blood cells in type 2 diabetes mellitus: higher vulnerability of polymorphonuclear leukocytes

Since oxidative stress is thought to play an important role in the pathogenesis and complications of diabetes, we used the comet assay (single cell alkaline gel electrophoresis) to evaluate DNA strand breaks and DNA base oxidation, measured as FPG (formamidopyrimidine DNA glycosylase)-sensitive sites, in peripheral blood cells (PBC) from type 2 diabetes patients and healthy controls. Oxidative DNA damage in leukocytes was increased in diabetic compared to normal subjects. However, no differences in the levels of DNA damage in isolated lymphocytes were found between the two groups. These data indicate a higher vulnerability to oxidative damage of polymorphonuclear as compared to mononuclear leukocytes in type 2 diabetes. Thus, the measurement of oxidative DNA damage in leukocytes by means of the comet assay is a suitable marker for the evaluation of systemic oxidative stress in diabetic patients.