Modified autonomic balance in offsprings of diabetics detected by spectral analysis of heart rate variability.
This study was performed to evaluate the influence of family history for non-insulin-dependent diabetes mellitus (NIDDM) on autonomic balance. The latter was assessed by spectral analysis of heart rate variability (SA-HRV) and by analyzing the relative contribution of low-frequency (LF) and high-frequency (HF) components. Twenty glucose normotolerant offsprings of NIDDM parents and 20 controls underwent a 1-hour continuous electrocardiogram (ECG). LF and HF (mean +/- SEM in normalized units [NU]), respectively increased and decreased in offspring versus controls. The LF/HF ratio (mean +/- SEM) significantly increased (LF/HF = 3.25 +/- 0.7 v 1.45 +/- 0.5, P <.0001 offsprings v controls). To test a stimulated response, a passive tilting (+ 90 degrees ) after 30 minutes of bed rest (0 degrees ) was performed in a subsample of subjects (10 offsprings v 10 controls). During bed rest, we found significantly higher values of the LF/HF ratio in offsprings versus controls (1.93 +/- 0.3 v 1.08 +/- 0.2, P <.05), whereas in the head-up position, the LF/HF ratio value increased to the same levels in the 2 groups (6.48 +/- 1.3 v 6.89 +/- 1.4, not significant [NS]). NIDDM family history is characterized in the basal condition by an imbalance of the autonomic system, which, compared with controls, is expressed by a higher weight of sympathetic and a lower weight of parasympathetic components. No significant differences can be found under stimulated conditions.