Background: Type-1 diabetes mellitus (T1-DM) is the commonest endocrine-metabolic disease in childhood. The prevalence of CD in type-1 DM ranges from 0.6 to 16.4% compared with 0.01–0.03% in the general population. The mechanism of association between the two diseases involves a shared genetic background of HLA genotype. Serum tissue transglutaminase IgA antibodies (tTG IgA) are considered specific and sensitive markers for screening of Celiac disease in more than 95 % of patients. Objective: Screening for the presence of serum tissue transglutaminase IgA antibodies (tTG ab) as a specific and sensitive biochemical marker for Celiac disease in patients with type-1DM and its relation to the clinical manifestations of those patients. Methods: One hundred-forty-nine patients with type-1 DM attending the out-patient clinic of endocrine and metabolism, Minia University Hospital were screened for the presence of serum tissue transglutaminase IgA antibodies during the period from March 2014 to November 2015. Results: Out of 149 patients 8 patients (5.3%) were positive for IgA tTG antibodies. They who were predominantly of female gender (75% were females). According to each age group, there were four sero-positive cases in children (with age group between 9 and ≤ 12 years); two cases in adolescents (with age group between 12 and ≤ 16 years) and two cases in adults (with age group 16-21 years). Intestinal manifestations, chronic diarrhea, recurrent abdominal pain/ distension, recurrent aphtha's stomatitis, anemia and bleeding tendency were significantly more common in seropositive cases (P=0.001, 0.001, 0.016, 0.00, 0.001and 0.04 respectively). All seropositive cases (100%) had lower BMIs than normal. There were no correlations between the tTG antibodies levels and HbA1c levels. Conclusions: The presence of tTG IgA antibodies is associated with significant changes in the clinical status of a patient with type-1 DM. Celiac disease-related manifestations like weight loss; anemia and chronic diarrhea were more common in seropositive diabetic patients. Serological screening for CD should be performed in all patients with type-1DM for early diagnosis and prevention of complications.