The aim of our study was to analyze the incidence and the clinical characteristic of celiac disease (CD) in pediatric population with type 1 diabetes mellitus (T1DM). Materials and methods: The data of 880 patients with T1DM, 429 girls, mean age 12.14 ±4.0 years was retrospectively retrieved from medical records. Patients with T1DM and CD were selected and a detailed analysis of CD prevalence and its clinical characteristic at the time of CD diagnosis was performed. The data were compared with the previous data from our center published a decade ago. Results: CD was suspected in 85/880 patients (9.65%) on the base of results of serological tests, but finally CD was diagnosed in 73/880 patients with T1DM (8.3%), in 53/429 girls (12.3%) and in 20/451 boys (4.4%). Most patients (71%) had CD diagnosed after T1DM onset. The majority of CD patients (72%) was asymptomatic. The CD diagnosis was not associated with inappropriate metabolic control of diabetes. The onset age of diabetes in children with CD was significantly lower than in those without CD (5.8 ±3.6 years vs. 7.56 ±4.0 years, p = 0.04). The prevalence of CD is significantly higher than a decade ago in our center (8.3% vs. 5.7%, p = 0.001). Conclusions: In light of increasing prevalence of mainly asymptomatic CD in patients with T1DM, CD screening is necessary. However positive serological tests, which are currently used in screening, and are the first step of diagnostics, in some patients allow only to suspect the CD and further diagnostic steps should be performed.