Introduction: Increased daytime blood pressure and reduced nocturnal dipping can already be found in children with type 1 diabetes mellitus. We hypothesized that impaired baroreflex sensitivity can cause this abnormal blood pressure behavior in children and adolescents with type 1 diabetes, reflecting an early stage of diabetic autonomic neuropathy.
Methods: In the present study, we monitored beat-to-beat blood pressure and pulse interval non-invasively with portapres in 38 patients with type 1 diabetes (7-18 yr) and 14 non-diabetic subjects (5-17 yr). The Trigonometric Regressive Spectral Analysis was used to assign spontaneous oscillations of blood pressure and pulse interval to defined frequency bands between 0.003 and 1.0 Hz and to calculate baroreflex sensitivity. Correlations with diabetes-specific data like hemoglobin A1c (HbA1c) and with 24-h blood pressure measurements were calculated.
Results: The diabetic subjects displayed significantly less variance of blood pressure and pulse interval in the high frequency (HF) bands and a lower BRS. BRS decreased with higher HbA1c and daily insulin dose. We also saw significant changes in spectral variance of blood pressure and pulse interval with these parameters. Patients with higher sympathetic activity (LF/HF-ratio) during daytime measurements displayed more nocturnal dipping.
Conclusion: Our data evidence impaired baroreflex sensitivity in children and adolescents with type 1 diabetes mellitus. We suggest spectral analysis of spontaneous blood pressure and pulse interval oscillations during night sleep to further pursue the role of baroreflex sensitivity in the etiology of the non-dipping phenomenon in diabetic patients.