We aimed to assess the growth, diabetes control, dietary intake and compliance with a gluten-free diet in children with insulin dependent diabetes mellitus (IDDM) and coeliac disease in a major paediatric and adolescent diabetes clinic. Children with IDDM and biopsy-proven coeliac disease aged <18 years were included and compared with IDDM controls matched for age, sex and duration of diabetes. Twenty patients with coeliac disease and IDDM participated (15 female, age 7.4-17.3 yr), with two matched IDDM controls for each (age 6.9-17.4 yr). The prevalence of coeliac disease in this diabetes clinic population was 2.6%. All patients completed a 3 day food record (3DFR) and a 7 day food frequency questionnaire (FFQ) to assess dietary intake and gluten-free compliance. Diabetes control measured by HbA1c was not different between groups or compared to the overall clinic population (8.48 +/- 0.98% for coeliac patients vs 8.87 +/- 1.46 for IDDM controls vs 8.60 +/- 1.30 for overall clinic population aged 5.0-17.9 yr). Height, weight and BMI standard deviation scores were not different between coeliac patients and IDDM controls. No clinically significant differences were found in intake of energy, macronutrients or micronutrients. The proportion of energy intake from carbohydrate, protein and fat was within recommended ranges, except for a higher saturated fat intake. Only 30% of coeliac patients complied with a strict gluten-free diet, but growth parameters were unaffected by dietary compliance. Thus, we found that children and adolescents with coexisting IDDM and coeliac disease have normal growth, equivalent diabetes control and no differences in energy or nutrient intake compared to matched IDDM controls in our clinic population.