Background The aim of this study was to compare the effect of glycaemic control on oxidative stress and biochemical markers of endothelial activation in type 1 diabetic children. Methods Serum total cholesterol, HDL cholesterol, VLDL cholesterol, apolipoprotein A1, apolipoprotein B, HbA 1c, MDA, VEGF, NO, ICAM levels were assessed in 100 children with type 1 DM aged 2–17 years. Study cases were evaluated in three groups in view of their mean HbA 1c values, as metabolically well-controlled (HbA 1c ≤ 8%) and poorly controlled (HbA 1c > 8%) patients with DM and 40 healthy children were included as normal controls. Results Levels of MDA, NO, VEGF, ICAM, apolipoprotein A1 and apolipoprotein B in metabolically poorly controlled diabetic patients were significantly higher than control group ( P < 0.05). In correlation analysis of HbA 1c to VEGF, no significant correlations were detected in metabolically well-controlled DM, but there were significant correlations between HbA 1c and NO, MDA, ICAM levels. In correlation analysis of HbA 1c to VEGF, NO, MDA and ICAM levels, significant correlations were detected in poorly controlled diabetics ( P < 0.05). Conclusions In the present study, increased levels of MDA, NO, ICAM-1 and VEGF levels showed that especially metabolically poorly controlled DM children are at high risk of atherosclerosis and vascular complications of DM and that there is a significant relationship between HbA 1c and oxidative stress. It may be appropriate to evaluate levels of VEGF and sICAM-1 as well as markers of oxidative stress in addition to routine laboratory assessments in evaluation of type 1 DM pediatric patients.