Cardiac autonomic neuropathy (CAN) is a common complication in diabetes mellitus (DM) and associated with increased mortality. Early detection of CAN is helpful for better individual risk stratification. The aim of this study was to screen autonomic dysfunction in children and adolescents with DM. We performed a retrospective study of pediatric patients with DM, aged 10-19 year. Autonomic function was assessed using five cardiorespiratory reflexes: heart rate, blood pressure response in standing position, hand gripping, deep breathing, and Valsalva maneuver. Total 29 children and adolescent patients (13 boys and 18 girls) with DM were included. 66% (N=19) of patients were diagnosed with type 1 DM. Pathologic cardiorespiratory reflexes (CRR) at least one item were seen in 14 patients (46.7%). In five CRR, the most frequent pathologic reflex was the response of heart rate in standing position (27.6%, n=8). Definite autonomic dysfunction (more than two pathologic reflexes in parasympathetic function) was found in two patients and severe autonomic dysfunction (definite autonomic dysfunction with pathologic reflexes in sympathetic function) was found in one patient. The patients with pathologic reflexes were younger than the patients with normal cardiorespiratory reflexes; The median age at diagnosis with DM and assessment of CRR was 11 and 18 year in the patients with pathologic reflexes, 14 and 19 year in the patients with normal reflexes (p0.05). In patients with pathologic cardiorespiratory reflexes, median duration of treatment was 35 months, mean hemoglobin A1c (HbA1c) was 11.7 ± 2.5% and the ratio of type 1 DM and type 2 DM 10:4. This was not significantly different from the value of patients with normal cardiorespiratory reflexes; duration of treatment 27 months, HbA1c level 10.7 ± 2.5 % and the ratio of type 1 DM and type 2 DM 11:4. In conclusion, autonomic dysfunction was common in pediatric patients with DM and more frequent and close assessment of CAN is needed for early diagnosis.