Type 1 Diabetes (T1D) patients present with gastrointestinal (GI) symptoms related to diabetes complications but also to other associated pathologies. In order to describe GI symptoms in patients with T1D, children, adolescents and adults were assessed as part of the screening phase of the Celiac Disease & Diabetes – Dietary Intervention & Evaluation Trial (CD-DIET). Individuals aged 8–35 years with T1D duration ≥1 year completed a self-reported questionnaire – Gastrointestinal Symptom Scale (GISS) to qualify for CD serology screening (www.celia-canddiabetes.com). GI symptoms were evaluated over the previous seven days, with an 9-item symptom questionnaire which included no symptoms, upper and lower abdominal pain, loss of appetite, nausea, loose or hard stool, vomiting and a Visual Analog Score (VAS, 0–100) to assess symptom severity. Age categories were defined as children 8–12 years, adolescents 13–18 years and adults 19–35 years. In total, 1095 patients completed the questionnaire; 283 (26%) children, 482 (44%) adolescents and 330 (30%) adults. Overall, 77% children, 79% adolescents and 79% adults reported no GI symptoms. In the group that had symptoms, adults most frequently reported lower (35%) and upper (28%) abdominal pain and loose stool (26%) while children reported lower (38%) and upper (44%) abdominal pain and nausea (26%) as main symptoms; similar to adolescents who referred lower (40%) and upper (34%) abdominal pain and nausea (13%) as main symptoms. Mean for the VAS score were low for all groups: 6.1/100 in children, 6.9/100 in adolescents and 6.2/100 for adults. In subjects reporting at least one GI symptom, a correlation between number of symptoms, severity and age group was seen, with adults reporting higher VAS scores for two symptoms (P=0.03) and ≥3 symptoms (P=0.02) compared to children. In conclusion, the frequency of GI symptoms was low in all groups of T1D subjects screened in clinic. The pattern of symptoms differed between the age groups and a stronger correlation was seen between number of symptoms and the severity in adults.