Cardiovascular autonomic reactivity is decreased in adolescents with Type 1 diabetes

To characterize autonomic nervous system function by means of the heart rate and blood pressure responses to various stimuli in relation to pubertal maturation in patients with Type 1 diabetes mellitus (DM).

One hundred out of 138 eligible patients at the Out-patient Diabetes Clinic and 100 healthy control subjects were examined in terms of cardiovascular parameters at rest, during deep breathing and when standing. Heart rate variability was analysed with time domain,frequency domain and fractal dimension parameters. Tanner pubertal staging was performed before the examinations.

The time domain parameters of heart rate variability at rest or during standing did not significantly differ between the patients and controls in total or at pubertal stages. In the spectral analysis of heart rate variability the very low frequency band was decreased in the patients during standing (P = 0.023).The increase in the very low frequency (P = 0.013)and low frequency (P = 0.031) spectral powers upon changing from a supine position to standing was attenuated in the patients in total, while no significant differences were observed within the Tanner pubertal stages between patients and controls. Heart rate variability during deep breathing was decreased in the patients with distal polyneuropathy (P = 0.006).

Although cardiovascular integrity is in the main well preserved in adolescent patients with Type 1 DM, these patients are prone to attenuated autonomic nervous system reactivity.