We report on the potential usefulness of the signal-averaged electrocardiogram (SA-ECG) in young patients with insulin-dependent diabetes mellitus (IDDM) to predict subclinical cardiovascular complications. Sixteen patients with IDDM and 18 age-matched healthy subjects were studied. The IDDM group included 4 males and 12 females, aged 7 to 20 y (mean 14.2 +/- 3.8 y, +/- SD). The duration from the onset of IDDM to the study ranged from 1.2 to 9.8 y (mean 5.4 +/- 3.8 y), and HbAlc value ranged from 6.6 to 12.4% (mean, 10.0 +/- 1.8%). SA-ECG was recorded and analyzed using the methods described by Simson. Values of filtered QRS duration (f-QRS), root mean square voltage (RMS), the duration of low amplitude signal (LAS) and late duration (LD) were calculated and compared between the groups. These parameters were not significantly different between the IDDM and control groups. However, in patients with poor glycemic control (HbAlc >10%), f-QRS was long and RMS was significantly low (p < 0.05, each) compared with the control group. Three patients with IDDM were positive for ventricular late potentials, although none had ventricular tachyarrhythmia. None of the control subjects showed ventricular late potentials.
Conclusion: Certain parameters of SA-ECG showed abnormal values in IDDM patients with poor glycemic control. Thus, SA-ECG is a potentially useful and non-invasive method for the assessment of subclinical cardiac impairment in diabetic children and adolescents.