Assessment of DNA strand breakage by comet assay in diabetic patients and the role of antioxidant supplementation

Diabetes patients often show increased production of reactive oxidative spe cies (ROS) together with vascular complications. The presence of these ROS may lead to increased DNA damage in peripheral blood lymphocytes that may b e revealed by the comet assay. To test whether DNA is damaged in diabetes, peripheral blood samples were taken from 30 control individuals and 63 diab etic patients (15 insulin dependent (IDDM) and 48 non-insulin dependent (NI DDM)) and the alkaline comet assay was used to evaluate background levels o f DNA damage. Significant differences were detected between control and dia betic patients in terms of frequencies of damaged cells. The extend of DNA migration was greater in NIDDM patients by comparison with IDDM patients wh ich might indicate that IDDM patients are handling more oxidative damage on a regular basis. Smoker individuals had higher frequencies of cells with m igration by comparison with the non-smokers in both groups. Also, clear dif ferences between patients on placebo and on Vitamin E supplementation for 1 2 weeks were observed on the basis of the extend of DNA migration during si ngle cell gel electrophoresis. (C) 2001 Elsevier Science B.V. All rights re served.