Ashgan Abdalla Alghobashy,1 Usama M Alkholy,1 Mohamed A Talat,1 Nermin Abdalmonem,1 Ahmed Zaki,2 Ihab A Ahmed,1 Randa H Mohamed3 1Department of Pediatrics, Faculty of Medicine, Zagazig University, Zagazig, Egypt; 2Department of Pediatrics, Faculty of Medicine, Mansura University, Mansura, Egypt; 3Department of Biochemistry, Faculty of Medicine, Zagazig University, Zagazig, Egypt Background: The early imbalances of trace elements in type 1 diabetes (T1D) may cause disturbance of glucose metabolism and more oxidative stress that may enhance the development of insulin resistance and diabetic complications. We aim to evaluate the serum level of selenium (Se), zinc (Zn), magnesium (Mg), and copper (Cu), the degree of oxidative stress and evaluate their relations to glycemic control in children with T1D. Methods: A case–control study which included 100 diabetic children and 40 healthy children age, sex, and ethnicity-matched as a control group. The diabetic children were divided into poor and good controlled patients according to glycosylated hemoglobin (A1c %). Studied children underwent history taking, clinical examination and laboratory measurement of serum Se, Zn, Mg, and Cu levels, erythrocyte reduced glutathione (GSH) and peroxidase enzyme activity (GPx). Results: Serum Se, Zn, Mg, Cu, erythrocyte GSH, and GPx were significantly lower in the diabetic group in comparison to the control group (P<0.05) and their levels were lower in poorly controlled patients compared to good controlled patients (P<0.05). The serum Se, Zn, Mg, erythrocyte GSH, and GPx showed a negative correlation with A1c %. The serum Se showed a positive correlation with erythrocyte GSH and GPx ([r=0.56, P<0.001], [r=0.78, P<0.001], respectively). Conclusion: Children with T1D, especially poorly controlled cases, had low serum Se, Zn, Mg, Cu, GSH, and GPx. Low serum Se in diabetic children may affect the erythrocyte GSH-GPx system. Keywords: oxidative stress; type 1 diabetes; trace elements, reduced glutathione, peroxidase