Abstract Numerous factors may influence the incidence of diabetes in the population. The production of reactive oxygen species (ROS) is elevated in diabetes patients. Based on the reported involvement of reactive species and nitrate/nitrite in diabetes, this present study has examined in the alkaline Comet assay, the effect of different levels of NaNO 2 in the presence of the oxygen radical generating agent, hydrogen peroxide (H 2O 2). Peripheral lymphocytes from diabetic and non-diabetic Caucasians and Asians of both sexes were studied in vitro. Endogenous factors (e.g., sex, age, body mass index—BMI) and exogenous factors (lifestyle factors e.g., smoking and drinking habits, diet) were taken into account. A preliminary study in two individuals showed that DNA damage remained constant over a wide dose range of NaNO 2 (1–75 mM), but when H 2O 2 was added at a constant concentration of 50 μM per dose of NaNO 2, there was an increase in DNA damage corresponding with the varying levels of NaNO 2 investigated. This was also seen with the 44 individuals (non-diabetic, n = 24; type 1 diabetic, n = 11; type 2 diabetic, n = 9) investigated. NaNO 2 was capable of inducing a significant level of DNA damage in lymphocytes ( p < 0.001), but only with the addition of H 2O 2. When levels of DNA damage were analysed in terms of the different variables there were few significant differences in damage between diabetic and non-diabetic subjects, or other sub-population groups, and no statistically significant differences in susceptibility were observed between subject covariates using regression techniques.