Dr Per Hagelqvist and team have found in a new study that in people with type 1 diabetes, both hypoglycemia brought on by exercise and hypoglycemia generated while at rest can lengthen both the QTc and TPE intervals.

The findings of this study were published in Diabetes Obesity and Metabolism Journal.
A growing body of research indicates that hypoglycemia, due to its prothrombotic and pro arrhythmogenic actions, is an independent risk factor for cardiovascular disease, which increases the risk of cardiovascular disease in people with type 1 diabetes and increases the risk of cardiac arrhythmias. In order to evaluate changes in cardiac repolarization during exercise-related hypoglycemia to hypoglycemia generated at rest in patients with type 1 diabetes, this research was done.

15 men with type 1 diabetes completed two distinct hyperinsulinaemic euglycaemic-hypoglycaemic clamp tests while receiving Holter-ECG monitoring as part of a randomized crossover research. In one investigation, falling plasma glucose levels were combined with a 60-minute period of moderate intensity cycling activity (PG; Clamp-exercise). In the other experiment, subjects were left at rest while hypoglycaemia was generated (Clamp-rest). The three steady-state phases of baseline (PG 4.0-8.0 mmol/L), hypoglycaemic phase (PG 3.0 mmol/L), and recovery (PG 4.0-8.0 mmol/L) were all evaluated, as well as the QTc interval, T-peak to T-end (Tpe) interval, and hormonal responses.
The key findings of this study were:
During the hypoglycaemic phase, both the QTc interval and the TPE interval dramatically rose from their starting points, although there was no discernible difference across test days.
On both days, these modifications were followed by a rise in plasma adrenaline and a fall in plasma potassium.
The QTc interval was longer during Clamp-rest compared to Clamp-exercise during the recovery phase, while the TPE interval was constant on the two test days.
Young males with type 1 diabetes who had exercise-related hypoglycemia and hypoglycemia that was produced at rest saw considerable QTc-interval prolongation and TPE-interval prolongation, which may temporarily enhance their vulnerability to ventricular arrhythmias. Therefore, the current study stresses how crucial it is to prevent hypoglycemia regardless of the amount of physical activity that was done before the occurrence.
The researchers concluded that exercise-related hypoglycaemia and hypoglycaemia induced at rest caused significant QTc-interval prolongation and Tpe-interval prolongation in young men with type 1 diabetes, which may lead to a transiently increased susceptibility to ventricular arrhythmias. Thus, the present study emphasizes the importance of avoiding hypoglycaemia regardless of the level of physical activity prior to the hypoglycaemic event.
Reference:
Hagelqvist, P. G., Andersen, A., Maytham, K. B., Andreasen, C. R., Engberg, S., Lindhardt, T. B., Faber, J., Holst, J. J., Forman, J. L., Pedersen‐Bjergaard, U., Knop, F. K., & Vilsbøll, T. (2023). Exercise‐related hypoglycaemia induces QTc‐interval prolongation in individuals with type 1 diabetes. In Diabetes, Obesity and Metabolism. Wiley. https://doi.org/10.1111/dom.14964