Alterations in heart rate variability during everyday life are linked to insulin resistance. A role of dominating sympathetic over parasympathetic nerve activity?

Table 2 Heart rate variability (HRV) frequency-, time- and poincaré parameters from the long-term 24-h ECG recordings during everyday life and daily activities in T2D relatives (n = 21) and control subjects (n = 21)

	Relatives (n = 21)	Controls (n = 21)	p value
Frequency domain indices
P_tot (ms², log)	3.50 (0.16)	3.61 (0.25)	0.02
P_VLF (ms², log)	3.28 (0.15)	3.38 (0.21)	0.03
P_LF (ms², log)	2.96 (0.23)	3.06 (0.32)	0.09
P_HF (ms², log)	2.47 (0.28)	2.58 (0.43)	0.10
P_LF/P_HF (log)	0.49 (0.17)	0.48 (0.26)	0.74
Time domain indices
SDNN	151 (24)	169 (45)	0.09
SDANN (ms)	137.8 (25.8)	150.7 (42.3)	0.21
SDNNindex	60.9 (11.0)	72.1 (21.4)	0.008
RMSSD (ms)	34.0 (11.3)	44.8 (22.1)	0.02
pNN50 (%)	10.0 (5.75)	16.2 (11.7)	0.006
Poincaré indices
SD1 (ms)	22.9 (6.7)	29.2 (13.8)	0.01
SD2 (ms)	212 (34)	235 (61)	0.09
SD1/SD2	0.11 (0.03)	0.12 (0.04)	0.08
RR interval (s) (average heart rate)	0.78 (0.08)	0.83 (0.08)	0.06

Five subjects missing, see methods section. Values are mean values and standard deviation (sd). Spectral indices are log-transformed. p values are derived from a comparison of relatives and controls analysis of variance (ANCOVA) of repeated measurements, adjusting for age. HRV heart rate variability, P _tot total power, P _VLF power of very low frequency component, P _LF power of low frequency component, P _HF power of high frequency component, P _LF /P _HF power of low frequency/power of high frequency ratio, SDNN is the standard deviation of all NN intervals, SDANN is the standard deviation of the consecutive 5-min averages of NN intervals, SDNNindex is the mean of the 5-min standard deviation of the NN intervals, RMSSD is the root mean square of successive differences of NN intervals, pNN50 is the proportion of differences in consecutive NN intervals >50 ms divided by the total number of NN intervals, SD1 and SD2 are two time-domain parameters calculated from Poincaré plots, i.e., scatterplots of each R–R interval against the consecutive value, SD1 describes the magnitude of the beat-to-beat variability, SD2 describes the fluctuations in mean RR interval over the 24-h period

ISSN: 1475-2840