Autonomic function testing in children and adolescents with diabetes mellitus.

Cardiac autonomic neuropathy (CAN) is a common complication in type 1 diabetes mellitus (T1DM) and associated with an increased mortality. Early detection of CAN would be desirable for a better individual risk stratification. The aim of this study was to determine whether autonomic dysfunction can be diagnosed in young patients with a recent history of T1DM. Autonomic function was assessed in 20 pediatric patients with T1DM, aged 10-19 yr, and a control group of 136 non-diabetic patients using four cardiorespiratory reflexes: heart rate and blood pressure response in standing position, deep breathing, and Valsalva maneuver. Furthermore, power spectral analyses of the low- and high-frequency band of heart rate variability (HRV) and baroreflex sensitivity (BRS) were tested with the non-invasive Task force monitor (CNSystems, Graz, Austria). Cardiorespiratory reflexes were pathologic for at least one item in 75% of the diabetic and 60% in the healthy control group. A reduced BRS was always combined with abnormal HRV. We found this pattern in 30% of diabetic patients and never in the control group. In patients with impaired BRS, mean hemoglobin A1c (HbA1c) was 7.7% and duration of diabetes 6.5 yr. This did not differ from the overall value of the diabetic group: HbA1c level 8.4% and diabetes duration 7.3 yr. In conclusion, signs of autonomic dysfunction are not uncommon in an early stage of diabetes in young patients. Classical cardiorespiratory reflexes seem to be less specific than HRV and BRS as testing methods.