Background: Type 1 diabetes mellitus (T1DM) is a chronic illness characterized by the body's inability to produce insulin due to the autoimmune destruction of the beta cells in the pancreas. Visfatin is a ubiquitous intracellular enzyme, known as nicotine amide phosphoribosyl transferase (NAMPT) and pre-B-cell colony-enhancing factor (PBEF-1). Objective: The aim of this study was to evaluate serum visfatin level in children and adolescent with type 1 diabetes mellitus (T1DM). Patients and methods: The present study was a case-control study observation that was conducted in Pediatric Endocrinology Unit, Pediatric Ward, Zagazig University Hospitals. The study included 46 children; 23 with T1DM and 23 healthy age- and sex- matched children.  Results: In this study, we found that serum visfatin level in diabetic group is statistically highly significant lower than healthy group. The mean serum level of visfatin in healthy group was 19.53 ± 10.5 ng/ml, while in T1DM patients was 2.85 ± 2.09 ng/ml. The best cutoff of serum visfatin level in excluding T1DM was ≥ 3.6 ng/ml with area under curve 0.968 with sensitivity 91.3%, specificity 82.6%, positive predictive value 84%, negative predictive value 90.5%, positive likelihood ratio 5.25, negative likelihood ratio 0.11 and accuracy 87% (p < 0.001). The result showed that serum visfatin could be helpful in prediction of T1DM among children and adolescents with an accuracy 87%. Conclusion: Serum visfatin level is lower in T1DM patients compared to healthy control. Visfatin play a role in early prediction and understanding the mechanism of its action in T1DM could lead to new therapeutic targets.