Objectives: The aim of this study was to investigate the role of zinc and HMGB1 alarmin in the development of Type 1 diabetes. The involvement of the high-mobility group box 1 pro- tein (HMGB1) in various autoimmune and inflammatory diseases has been documented be- fore. However, the role of this proinflammatory molecule in children with diabetes type 1 (T1DM) has not been clarified so far. The aim of this study was to compare the level of serum HMGB1 in children within the early (Group 1) and late (Group 2) stages of T1DM, with the control group of children without T1DM or any other autoimmune disease. Study design: A cross-sectional study. Participants: The study included 141 children: Group 1 (N=28), Group 2 (N=73) and Con- trol group (N=40). Materials and Methods: The measurements were made on serum samples for: HMGB1, zinc, white blood cell count, C-reactive protein, glucose, haemoglobin A1C, and β-cells autoanti- bodies (GADA-65, IA-2, ICA). Results: The children with T1DM had a statistically significant higher serum levels of HMGB1 (experimental group: 8.7 µg/l) compared to the children without T1DM (control group: 1.0). The HMGB1 level was statistically higher in children with a longer disease dura- tion (Group 1: 4.9 µg/l; Group 2: 8.7 µg/l, P <0.001). The children with T1DM had signifi- cantly lower zinc levels (10.7) compared to the control group (12.85). Comparing the zinc values according to the duration of diabetes, the subjects with diabetes which lasts for more than two years have the significantly lowest mean zinc levels (10.3 of the interquartile range 9 – 11.7). Conclusion: The higher level of HMGB1 in children with T1DM indicates that this proin- flammatory molecule can serve as an inflammatory biomarker in patients with diabetes and may be a better marker compared to other inflammatory reactants.