QTc interval prolongation and QTc dispersion in children and adolescents with type 1 diabetes.

Objectives: To evaluate whether QT interval, QT interval corrected for heart rate (QTc), and QTc dispersion changes are already present in children and adolescents with diabetes.

Study Design: QT interval, QTc, and QTc dispersion were measured on a 12-lead surface electrocardiogram in 60 children and adolescents with stable type 1 diabetes and in 63 sex- and age-matched control subjects. Differences were evaluated by using the Kolmogorov-Smirnov Z test. The number of patients with QTc > 440 ms was compared in the two groups. The possible influence of age, sex, diabetes duration, and glycosylated hemoglobin (HbA(1c)) was examined by using Spearman correlation analysis.

Results: Diabetic children had significantly longer QTc intervals and a significantly larger QTc dispersion. The number of individuals with a QTc >440 ms was significantly higher in the diabetic group (14/60) than in the control group (2/63). The effect of age on R-R interval and QTc dispersion in healthy children was less pronounced in children with diabetes. HbA(1C) values did not significantly correlate with any of the parameters.

Conclusions: QTc prolongation and a larger QTc dispersion are already present in a significant proportion of children and adolescents with diabetes.