Related Experiment Videos
Altered ventricular repolarization during hypoglycaemia in patients with diabetes
J L Marques1, E George, S R Peacey
1Department of Medical Physics and Clinical Engineering, Royal Hallamshire Hospital, Sheffield, UK.
Summary
Hypoglycaemia, or low blood sugar, prolongs the QT interval on ECGs in patients with diabetes. This QT lengthening, linked to adrenaline surges, may explain sudden overnight deaths in young patients with insulin-dependent diabetes mellitus (IDDM).
Area of Science:
- Cardiology
- Endocrinology
- Diabetology
Background:
- Sudden unexplained death in young patients with Type 1 diabetes suggests a link to nocturnal hypoglycemia.
- The precise mechanism by which hypoglycemia might cause fatal arrhythmias remains unknown.
Purpose of the Study:
- To investigate the effects of induced hypoglycemia on electrocardiogram (ECG) parameters in patients with Type 1 diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM).
- To explore potential mechanisms, including changes in plasma potassium and adrenaline, associated with hypoglycemia-induced ECG alterations.
Main Methods:
- A randomized, crossover study involving 15 diabetic patients (8 IDDM, 7 NIDDM) undergoing hyperinsulinemic glucose clamps.
- Participants experienced controlled periods of euglycemia (normal blood sugar) and hypoglycemia (around 3 mmol/L) on separate visits.
- Electrocardiograms (ECG) were monitored for corrected QT interval (QTc), with measurements of plasma potassium and adrenaline at baseline and intervals up to 120 minutes.
Main Results:
- Hypoglycemia caused significant QT interval lengthening in both IDDM and NIDDM patients compared to euglycemic periods.
- A greater fall in plasma potassium was observed during hypoglycemia in NIDDM patients.
- Hypoglycemia led to increased plasma adrenaline levels in both groups, strongly correlating with QT interval prolongation (r = 0.73, p <0.0001).
Conclusions:
- Induced hypoglycemia alters ventricular repolarization, evidenced by significant QT interval prolongation.
- The observed QT lengthening, driven by hypoglycemia and associated adrenaline release, offers a potential mechanism for cardiac arrhythmias and sudden death in diabetic patients.