Reactive oxygen species involved in oxidative stress may damage DNA, the biopolymer that contains the genetic information. The cell has developed several enzymatic systems to repair the damage but some of them may persist and lead to mutagenesis. We focused our attention on the simultaneous quantification of several DNA lesions using the highly sensitive, specific and reliable high performance liquid chromatography-electrospray ionization tandem mass spectrometry detection technique (HPLC-MS/MS). The aim of this work is to determine if the different measured DNA lesions could be used as biomarkers of in vivo oxidative stress and/or inflammation. For such a purpose, three different types of DNA lesions were monitored: oxidized DNA lesions, chlorinated nucleosides arising from inflammation processes and DNA adducts generated from reaction with reactive aldehydes arising from lipid peroxides breakdown. Preliminary results, that have to be further confirmed, show a significant increase in the level of several different DNA lesions in diabetic patients versus a control group of healthy volunteers.