Objective To evaluate the influence of biopsy-proven celiac disease (BPCD) on somatic development and metabolic parameters in children with type 1 diabetes mellitus (T1DM) in a multicenter survey. Study design Within the Diabetes Patienten Verlaufsdokumentationssystem–Wiss project, data of 41 951 patients with T1DM, aged <20 years (52% males, mean age 13.9 years; mean duration of diabetes 5.5 years) were collected in 297 centers in Germany and Austria from 1995 to 2009. Results The number of BPCD (0.6% in 1995; 1.3% in 2008) has increased over time. Patients with BPCD were significantly younger at diabetes onset (5.9 vs 8.3 years), had a significantly lower weight standard deviation score (SDS); (0.20 vs 0.43) and height SDS (-0.28 vs -0.03) ( P < .001, each) compared with patients without celiac disease. No differences were found in hemoglobin A1c or numbers of severe hypoglycemia. In a subgroup of 9805 patients (183 with BPCD) significantly lower height and weight SDS ( P < .001) were still found after a 5-year follow-up. Conclusions Screening for celiac disease is important in children with T1DM to prevent persistent growth failure.