Summary: In a randomized crossover clamp study, hypoglycemia prolonged the QTc interval in healthy adults and in people with type 2 diabetes after repeated hypoglycemic exposure. QTc returned to baseline within 90 minutes of euglycemia.
PICO Summary
| Element | Detail |
|---|---|
| Population | 27 healthy participants and 16 participants with type 2 diabetes studied with hyperinsulinemic clamps. |
| Intervention | Experimental hypoglycemia; healthy participants also received hypoglycemia after mineralocorticoid receptor blockade. |
| Comparator | Euglycemia in the healthy-participant crossover comparison; morning baseline in the type 2 diabetes group. |
| Outcomes | In healthy participants, morning QTc was 439.06 versus 406.96 ms and afternoon QTc was 441.50 versus 407.78 ms during hypoglycemia versus euglycemia. QTc recovered by 90 minutes. |
| Study design | Double-blind crossover clamp study in healthy participants and a hypoglycemia exposure study in type 2 diabetes. |
Hypoglycemia and QTc
Randomized clamp study
Hypoglycemia transiently prolonged QTc in healthy participants and people with type 2 diabetes, with recovery after euglycemia and no prevention from mineralocorticoid receptor blockade.
Expert Commentary
This mechanistic study reinforces why hypoglycemia is more than a glucose-number problem. Insulin-induced hypoglycemia prolonged QTc in healthy participants by about 32 to 34 ms compared with euglycemia. In the type 2 diabetes group, QTc prolongation became significant after the afternoon hypoglycemic exposure, and mineralocorticoid receptor blockade did not prevent the response. QTc returned to baseline within 90 minutes after euglycemia, with no apparent next-day residual effect. The findings are physiologically coherent but do not establish an increase in torsades, sudden death, or other clinical arrhythmias.
Can I use this with my patients? Yes, as supporting evidence for preventing and promptly treating hypoglycemia, especially in patients with structural heart disease, QT-prolonging medicines, electrolyte abnormalities or recurrent nocturnal episodes. It should not be used to justify routine ECG monitoring for every person with diabetes or to infer that a transient QTc change is itself a clinical event. The sample was small, the clamp setting was artificial, and the diabetes cohort did not complete the same crossover comparisons as the healthy cohort. Clinicians should focus on individualized glucose targets, medication review, education, continuous glucose alerts where appropriate, and correction of potassium or magnesium abnormalities. The practical message is risk reduction and rapid recovery, not a new screening test.
References
Haas AV, Koefoed AW, Celli J, Bonyhay I, White J, Meyer KM, et al. Effect of Hypoglycemia on QT Interval in Individuals With and Without Type 2 Diabetes: A Randomized Crossover Trial. J Clin Endocrinol Metab. 2025. doi:10.1210/clinem/dgae919. PMID: 39787048.