: The etiology of type 1 diabetes mellitus (DM1) is not fully understood. Some studies indicate an excess or deficiency of certain trace elements may affect glucose and insulin metabolism. This study aimed to assess the concentrations of trace elements in children with newly diagnosed DM1. The study group comprised 35 children aged 3-17 years (mean, 8.83±3.55 years). Serum concentrations of selenium, zinc, copper, and arsenic were determined at the time of diagnosis, after ~2 weeks (during insulin treatment), and after 6 months. No trace element deficiency was observed. Selenium levels were increased at all time points (77.61±14.03 µg/l; 70.42±11.04 µg/l; 75.79±12.89 µg/l). Arsenic levels were increased at the time of discharge (0.30±0.24 µg/l) and upon 6 months control visit (0.67±1.98 µg/l) for DM1. Copper levels were elevated at the time of diagnosis (1333±244 µg/l). No significant differences were observed in zinc concentrations between study and control group or between time points. Trace elements in the environment, especially selenium, may increase the incidence of DM1, although further research is required to confirm this association.