Objective To investigate the oxidative stress state in children with diabetic ketoacidosis (DKA),and analyze whether any observed abnormalities were related to metabolic disturbances.Methods Four groups of subjects were studied,comprising with 22 patients with DKA(group 1),18 diabetic children with medium metabolic control,whose glycated hemoglobin(HbAlc) below 9%(group 2),22 children with poorly controlled diabetes,whose Hbal c above 9%(group 3),and 36 healthy control children(group 4).Malondialdehyde(MDA),nitrate oxidase(NO),glutathione peroxidase(GSH-Px),superoxide dismutase(SOD),and metabolic parameters such as fasting blood glucose,HbAlc,blood gas analysis,serum ion,renal function of the subjects were measured.Results Mean serum MDA value was significantly higher in group 1 than in group 2(P ＜0.01) and group 4(P ＜0.01),but was not different from that in group 3 (P ＞0.05).Serum levels of NO were significantly higher in group 1,2 and 3 compared with group 4(P＜0.01).Serum levels of GSH-Px were significantly lower in group 1,2 and 3 than in group 4(P＜0.01).There were no significant differences of serum SOD value among the four groups(P＞0.05).Both serum MDA and NO values in the diabetic patients(groups 1 +2 +3) were positively related to HbAlc(r=0.375,P ＜0.01;r=0.250,P ＜0.05),and serum SOD values in the DKA patients were negatively related to HbAlc(r= -0.507,P＜0.05),there were not any significant relationship between the other oxidative markers and metabolic parameters.Conclusion There is an increase of oxidative stress and decrease of antioxygenic ability in DKA children,and these changes tend to correlate more with markers of diabetic imbalance than with parameters of acute metabolic disturbances of DKA.