Frequency of Hypoglycemia in Children With Beta-blocker Treated Long QT-syndrome

NCT07233421 | Enrolling By Invitation DMC

• 1 other identifier: HUS/2446/2024
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this observational study is to investigate the frequency and characteristics of hypoglycemic episodes in children with long QT syndrome (LQTS) and beta-blocker treatment, specifically those receiving propranolol, compared to healthy controls. The study focuses on children under seven years with genetically confirmed LQTS and beta-blocker therapy, as well as healthy siblings as controls. The main questions it aims to answer are:

• Does hypoglycemic episodes occur in children with LQTS who are treated with propranolol?
• Are there asymptomatic episodes of low blood glucose that could affect well-being and neurological development?
• Are there individual differences in susceptibility to hypoglycemia, and do genetic factors explain these differences?
• What is the incidence of hypoglycemia leading to emergency visits or hospitalizations among LQTS patients compared to healthy controls? Researchers will compare children with LQTS on propranolol to healthy siblings to see if the frequency and severity of hypoglycemia differs between groups. Participants will: Have a Dexcom G7 continuous glucose monitor installed to record glucose profiles for ten days, both during an healthy episode and during an infection (when risk for hypoglycemia is increased). If differences in susceptibility to hypoglycemia are observed, genetic data from the Helsinki biopank will be analyzed to explore potential genetic factors underlying these differences. Visits to emergency clinic and hospitalizations due to hypoglycemia will be retrospectively reviewed for all LQTS patients under 16 years old and compared to healthy controls. Additional Details: The study is conducted at Helsinki University Hospital (HUH) Children and Adolescents and the New Children's Hospital clinical research unit. The study aims to recruit 20-40 LQTS patients and 10 healthy controls. The study is ethically justified, with no extra laboratory tests or costs for participants, and written consent will be obtained from parents and capable children. The results are expected to improve the safety of propranolol treatment in LQTS children by identifying risk factors for hypoglycemia and informing preventive strategies, such as dietary guidance, use of glucose monitoring devices during illness, or considering selective beta-blockers for high-risk patients.

Conditions

Long QT Syndrome; Hypoglycemia

Keywords

propranolol; beta blocker; hypoglycemia; long qt syndrome

Outcome Measures

Primary Outcomes (1)

• Time spent in low glucose (<3.9 mmol/l)

  Time spent in low glucose (\<3.9 mmol/l) in GCM will be compared within the LQT patient group (during healthy episode vs during an infection)

  10 days continuous glucose monitoring

Secondary Outcomes (4)

• Difference in time spent in very low glucose (<3.1 mmol/l)

  10 days continuous glucose monitoring

• Time spent in low glucose (<3.9 mmol/l) between groups

  10 days continuous glucose monitoring

• Nuber of finger prick confirmed hypoglycemic episodes

  10 days continuous glucose monitoring

• Number of participants with adverse outcomes at the device site

  10 days continuous glucose monitoring

Study Arms (2)

Long QT-syndrome patients

OTHER

Children (aged 0-6 years) with genetically verified LQT1 or LQT2

Device: Continuous Glucose Monitoring

Controls

OTHER

0-6 year old healthy siblings of long QT-syndrome patients

Device: Continuous Glucose Monitoring

Interventions

Continuous Glucose Monitoring DEVICE

All participants will have the continuous glucose monitoring device Dexcom G7 placed. The Dexcom G7 Glucose Monitoring System reports continuous interstitial blood glucose concentrations every 5 minutes and alerts for low glucose (\<3.1 mmol/l). Sensor low alarms are verified by finger prick tests. A single sensor is used up to 10 days and the sensoring is performed twice in each participant.

Controls; Long QT-syndrome patients

Eligibility Criteria

• Age: Up to 7 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• Study group: children under 7 years of age with genetically confirmed LQTS (types 1 or 2) and on beta-blocker medication
• Control group: healthy children (siblings of LQTS patients)

You may not qualify if:

• Children with diabetes, inherited diseases of inborn error of metabolism, tube feeding, gastrointestinal operations with risk for dumping, medications leading to hypoglycemia, dialysis, or any severe acute illness

Sponsors & Collaborators

• Helsinki University Central Hospital: lead
• Foundation for Paediatric Research, Finland: collaborator

Study Sites (1)

New Children's Hospital, Helsinki University Hospital

Helsinki, Finland

Location

Related Publications (4)

• Carnovale C, Gringeri M, Battini V, Mosini G, Invernizzi E, Mazhar F, Bergamaschi F, Fumagalli M, Zuccotti G, Clementi E, Radice S, Fabiano V. Beta-blocker-associated hypoglycaemia: New insights from a real-world pharmacovigilance study. Br J Clin Pharmacol. 2021 Aug;87(8):3320-3331. doi: 10.1111/bcp.14754. Epub 2021 Feb 23.

  PMID: 33506522 BACKGROUND

• Poterucha JT, Bos JM, Cannon BC, Ackerman MJ. Frequency and severity of hypoglycemia in children with beta-blocker-treated long QT syndrome. Heart Rhythm. 2015 Aug;12(8):1815-9. doi: 10.1016/j.hrthm.2015.04.034. Epub 2015 Apr 27.

  PMID: 25929701 BACKGROUND

• Torekov SS, Iepsen E, Christiansen M, Linneberg A, Pedersen O, Holst JJ, Kanters JK, Hansen T. KCNQ1 long QT syndrome patients have hyperinsulinemia and symptomatic hypoglycemia. Diabetes. 2014 Apr;63(4):1315-25. doi: 10.2337/db13-1454. Epub 2013 Dec 18.

  PMID: 24357532 BACKGROUND

• Koponen M, Marjamaa A, Hiippala A, Happonen JM, Havulinna AS, Salomaa V, Lahtinen AM, Hintsa T, Viitasalo M, Toivonen L, Kontula K, Swan H. Follow-up of 316 molecularly defined pediatric long-QT syndrome patients: clinical course, treatments, and side effects. Circ Arrhythm Electrophysiol. 2015 Aug;8(4):815-23. doi: 10.1161/CIRCEP.114.002654. Epub 2015 Jun 10.

  PMID: 26063740 BACKGROUND

MeSH Terms

Conditions

Long QT Syndrome; Hypoglycemia

Interventions

Continuous Glucose Monitoring

Condition Hierarchy (Ancestors)

Arrhythmias, Cardiac; Heart Diseases; Cardiovascular Diseases; Cardiac Conduction System Disease; Heart Defects, Congenital; Cardiovascular Abnormalities; Congenital Abnormalities; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases

Intervention Hierarchy (Ancestors)

Blood Chemical Analysis; Clinical Chemistry Tests; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Techniques, Endocrine; Monitoring, Physiologic; Investigative Techniques

Study Officials

• Elina Hakonen, MD, PhD

  New Children's Hospital, Helsinki University Hospital

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MD PhD Pediatrician

Study Record Dates

• First Submitted: November 14, 2025
• First Posted: November 18, 2025
• Study Start: December 9, 2024
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): December 31, 2027
• Last Updated: November 18, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will not share

Locations

FI (1)