Abstract 3762: Effects of Controlled Hypoglycemia on Cardiac Repolarization in Type 1 Diabetes
Background: Nocturnal hypoglycemia may contribute to sudden death in diabetic patients. However, it is not well known why hypoglycemia makes these patients prone to death.
Methods: We assessed the effects of controlled hypoglycemia on cardiac repolarization using novel electrocardiographic descriptors of T-wave and QRS complex morphology in 16 type 1 diabetic patients and their 8 healthy counterparts. Several electrocardiographic variables characterizing repolarization were analyzed from digitized 12-lead electrocardiograms during both an euglycemic and a hypoglycemic clamp.
Results: Hypoglycemia did not result in significant changes either in the QT interval corrected for heart rate by the nomogram method or in QT dispersion. However, the morphology of the T-wave changed significantly during hypoglycemia. The T-wave amplitude and area in precordial leads decreased significantly in both groups (p-values from <0.05 to <0.001). The spatial QRS-T angle (TCRT) (p<0.05) and the height and the width of the T-wave loop (p<0.05 and p<0.01, respectively) also reduced in the diabetic patients. The changes in the repolarization parameters did not exhibit any significant association with changes in catecholamine levels, or in heart rate variability in either group.
Conclusion: Hypoglycemia results in distinct alterations in cardiac repolarization which may increase the vulnerability to arrhythmic events.