Short-term frequency and time domain analysis of heart rate variability in type I diabetic subjects.

Assessment of heart rate variability as a measure of sympathovagal balance has proven useful in the risk stratification of patients with coronary artery disease. Since diabetic subjects with autonomic neuropathy, carrying a high risk of cardiovascular events, have been shown to have reduced heart rate variability, we performed a short-term (600 RR-intervals) frequency and time domain analysis in type I diabetic subjects. 19 patients without clinical signs of autonomic neuropathy were compared with 11 age- and sex-matched control persons. At a comparable cycle length, diabetic subjects differed significantly from healthy controls in all calculated time domain parameters (standard deviation: 41 +/- 23 vs. 66 +/- 17 ms, p = 0.005; root mean square successive difference of normal RR-intervals: 25 +/- 17 vs. 41 +/- 17 ms, p = 0.02) and frequency domain parameters (low frequency: 58 +/- 67 vs. 158 +/- 97 ms2, p = 0.002; high frequency: 29 +/- 42 vs. 85 +/- 96 ms2, p = 0.03). Thus, short-term frequency and time domain analysis of heart rate variability can be used easily and quickly in an outpatient setting for estimation of changes in the sympathovagal balance in diabetic subjects. However, the prognostic significance and the influence of drugs on impaired heart rate variability in diabetic subjects have yet to be determined.