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 | |||
| Ptot (ms2, log) | 3.50 (0.16) | 3.61 (0.25) | 0.02 |
| PVLF (ms2, log) | 3.28 (0.15) | 3.38 (0.21) | 0.03 |
| PLF (ms2, log) | 2.96 (0.23) | 3.06 (0.32) | 0.09 |
| PHF (ms2, log) | 2.47 (0.28) | 2.58 (0.43) | 0.10 |
| PLF/PHF (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