Changes in cardiac repolarization during clinical episodes of nocturnal hypoglycaemia in adults with Type 1 diabetes
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Aims/hypothesis Experimental hypoglycaemia leads to abnormal cardiac repolarization manifest by a lengthened QT interval and caused by adrenergic stimulation. However it is less clear whether spontaneous clinical episodes lead to similar changes. We have therefore measured cardiac ventricular repolarization and counterregulatory responses in patients with Type 1 diabetes during hypoglycaemic and euglycaemic nights.Methods We studied 22 patients with Type 1 diabetes (mean age 40.4+/-17.2 years, duration of diabetes 17.2+/-9.3 years, HbA1c 8.2+/-1.2% overnight). Measurements were taken hourly of blood glucose, plasma potassium, catecholamines and high resolution electrocardiograms.Results Hypoglycaemia (blood glucose level <2.5 mmol/l) occurred on 7 of the 22 nights. During overnight hypoglycaemia, QTc interval increased by 27 ms (+/-15) above baseline, compared with 9 ms (+/-19) during nights with no nocturnal hypoglycaemia (p=0.034, 95%CI 2, 35). Adrenaline increased by 0.33 nmol/l (+/-0.21) above baseline during hypoglycaemia, compared with -0.05 nmol/l (+/-0.08) during euglycaemia (p=0.001, 95%CI 0.19, 0.56 nmol/l). There was no significant difference between potassium, and noradrenaline concentrations between the two groups.Conclusion/interpretation QTc interval lengthens significantly during spontaneous nocturnal hypoglycaemia. Increases are generally less than those observed during experimental hypoglycaemia and could reflect attenuated sympathoadrenal responses during clinical episodes. The clinical relevance of these changes is uncertain but is consistent with the hypothesis that clinical hypoglycaemia can cause abnormal cardiac repolarization and an attendant risk of cardiac arrhythmia.
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Around 60-70% of nocturnal hypoglycemic episodes in patients with diabetes occur during late sleep, i.e., between 03:00 and 07:00 h.
“Around 60–70% of nocturnal hypoglycemic episodes in patients with diabetes occur during late sleep, i.e., between 03:00 and 07:00 h [ 35 , 36 ].”
From Hypoglycemia Unawareness—A Review on Pathophysiology and Clinical Implications (2024) · cites this paper as [35]
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References 19 · Cited by 137
- Authors
- Robinson, R. T. C. E., Harris, N. D., Ireland, R. H., Macdonald, I. A., & Heller, S. R.
- Affiliations
- University of Sheffield (GB)
- Royal Hallamshire Hospital (GB)
- University of Nottingham (GB)
- Northern General Hospital (GB)
- Corresponding author
- Heller, S. R.
- Venue
- Diabetologia
- Published
- 2004-02-01
- Volume
- 47
- Issue
- 2
- Pages
- 312-315
- ISSN
- 0012-186X (ISSN-L)
- 1432-0428
- OpenAlex
- W2043485791
- Cited by
- 137
- References
- 19
- Citations by year
- 2026: 1 · 2025: 2 · 2024: 4 · 2023: 4 · 2022: 2 · 2021: 7 · 2020: 8 · 2019: 2 · 2018: 7 · 2017: 9 · 2016: 5 · 2015: 8 · 2014: 10 · 2013: 11 · 2012: 9
- FWCI
- 2.89
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- www.springer.com/tdm (tdm)
- Locations
- Diabetologia (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Diabetes UK
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Management and Research
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac electrophysiology and arrhythmias
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Treatment and Management
- Keywords
- nocturnal hypoglycemia, type 1 diabetes, cardiac repolarization, QTc interval, counterregulatory response, epinephrine, sympathoadrenal response, arrhythmia risk, catecholamines
- MeSH terms
- Adult, Blood Glucose, Cardiovascular Physiological Phenomena, Circadian Rhythm, Diabetes Mellitus, Type 1, Electrocardiography, Epinephrine, Humans, Hypoglycemia, Middle Aged, Potassium, Sleep
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