Özet:
Heart rate variability (HRV) is a noninvasive index of the neural activity of the
heart. Although also influenced by the sympathetic activity of the heart, HRV is essentially
determined by the vagal stimulation of the heart. Several HRV abnormalities have been described
in adults with diabetes mellitus. However, there are few data on HRV in children with
diabetes mellitus. In the present study, HRV was assessed in seven healthy children, 10 diabetic
children with good glycemic control and 11 diabetic children with poor glycemic control. All had
normal standard cardiac autonomic function tests, obtained from 24-h Holter tapes. HRV was
measured by calculating six time-domain (mean R-R interval (RR), standard deviation of the
R-R interval [SDRR], standard deviation of the mean of 288 R-R intervals [SDANN], the
mean of the 288 standard deviations computed for each 5-rain period [SD], percentage of
differences of adjacent R-R intervals of >50 msec for the entire 24 h [pNN50], and the root
mean square of successive differences [rMSSD]) and four frequency-domain (low frequency
[LF], high frequency [HF], total heart rate power spectra, and LF/HF ratio) indexes. SD,
pNN50, rMSSD, LF, HF and total heart rate power spectra were markedly and significantly
reduced in diabetic children with poor metabolic control. The 24-h variation of low- and highfrequency
components of heart rate power spectra of the latter children had a different shape.
Thus, diabetic children with poor metabolic control (elevated HbAlc and B2M levels) have a
low HRV compared to those diabetic children with good control and healthy children. These
results can be interpreted as evidence of cardiac autonomic neuropathy in diabetic children with
asymptomatic diabetic autonomic neuropathy.
