BACKGROUND: Oxidative stress, lipid peroxidation and immune response to oxidized low density lipoprotein(oxLDL) are important events in the progression of atherosclerosis in diabetes mellitus(DM). Though, many clinical studies used man-made reagents that the reproducibility of the tests was not reliable and showed controversial results in some aspects. We performed above three tests in DM patients by the commercial kits and compared our results with previous results. METHODS: Total 67 DM patients and sex- and age-matched healthy persons were tested about total antioxidant status(TAS), lipid peroxidation(LPO) and autoantibody to oxLDL(anti-oxLDL) by Total Antioxidant Status kit(RANDOX Labs., Crumlin, UK), BIOXYTECH LPO-586 kit(OXIS International Inc., Portland, OR, USA) and Ox-LDL IgG ELISA kit(BIODESIGN International, Kennenbunk, ME, USA) each. RESULTS: The intra-run and between-run coefficients of variation of TAS and LPO were 2.6/2.7% and 13.4/15.6% respectively. The intra-run coefficient of variation of anti-oxLDL was 1.8 to 6.9%. DM patients showed decreased TAS(1.31+/-0.15 mmol/L) when compared with normal controls(1.38+/-0.09 mmol/L, P <0.01). TAS was inversely correlated with HbA1c(r=-0.38, P <0.01). LPO and anti-oxLDL in DM patients did not differ significantly from normal controls. CONCLUSIONS: By commercial kits, we could get reproducible results of TAS and anti-oxLDL, but not LPO test. The results of TAS and HbA1c among the DM patients and normal controls suggested that poor glycemic control might be associated with decrease of TAS. We could not find significant difference in the results of LPO and anti-oxLDL between two groups.