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NCT Number: NCT06852612

Dietary Treatment Strategies and Metabolic Control in Glycogen Storage Disease Type I

The present project will specifically assess metabolic effects of dietary interventions with controlled intake of fructose and fructose/galactose in GSDI, with the aim to provide evidence whether relaxed dietary restrictions of fructose and galactose may be justified in treatment recommendations at least for adults, which would considerably enlarge food choice in everyday life of the patients with an expected positive impact on the quality of life of patients with this rare disorder.

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Key information

Conditions

Glycogen Storage Disease Type I Carbohydrate Metabolism, Inborn Errors Congenital, Hereditary, and Neonatal Diseases and Abnormalities Genetic Diseases, Inborn Glycogen Storage Disease Metabolic Diseases Metabolism, Inborn Errors Nutritional and Metabolic Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital, Bern, Switzerland

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About this study

To assess relaxed restriction of fructose and fructose/galactose intake on secondary metabolic alterations in GSDI, (i) by looking at the traditional parameters for assessing metabolic control in clinical chemistry (lactate, triglycerides, uric acid), and (ii) by using a broad analytical approach relying on targeted metabolomics/lipidomics.

It is hypothesized that relaxed restrictions on the intake of fructose and/or galactose as part of the diet in everyday life may lead to an increase in blood lactate levels (=primary outcome), triglycerides, and uric acid to a certain degree compared to baseline. However, this increase is expected to remain within a range that is not clinically relevant for adult patients, especially when fructose/galactose intake is not excessive and stays within the usual daily allowances for healthy individuals, as planned in this study.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Genetically and/or enzymatically confirmed diagnosis of GSDI (GSDIa or GSDIb)
  • Male or female ≥ 18y
  • Restriction of fructose intake in usual dietary treatment
  • Written informed consent

Exclusion criteria

  • Non-compliance with routine dietary treatment
  • Pregnancy or lactation
  • Liver transplant
  • Recurrent hospitalisations due to metabolic decompensation within the last 12 months
  • Severe chronic kidney disease with glomerular filtration rate (GFR) < 30 ml/min
  • For GSDIb: Severe, uncontrolled symptomatic inflammatory bowel disease

Treatment and study plan

Fructose

Dietary Supplement

40g fructose (free and bound, max amount of fructose from added free sugar/saccharose 25g)

Fructose and galactose

Dietary Supplement

10g galactose (mostly from lactose) plus 40g of fructose (free and bound, max amount of fructose from added free sugar/saccharose 25g)

Primary outcomes

  1. Change in lactate during the dietary intervention compared to baseline under the usual diet

    Time frame: 4 Weeks

    Lactate belongs to the parameters of secondary metabolic disturbance traditionally used to estimate metabolic control in GSDI in routine clinical practice (lactate, triglycerides, uric acid). Redundant measurements of lactate are performed in blood as well as in collected urine.

Secondary outcomes

  1. Change in plasma triglycerides during the dietary intervention compared to baseline (as parameters traditionally measured together with lactate to estimate overall metabolic control)

    Time frame: 4 Weeks

  2. Change in plasma uric acid during the dietary intervention compared to baseline (as parameters traditionally measured together with lactate to estimate overall metabolic control)

    Time frame: 4 Weeks

  3. Plasma metabolite changes in targeted metabolomics during the dietary intervention compared to baseline measurements.

    Time frame: 4 Weeks

  4. Plasma metabolite changes in targeted lipidomics during the dietary intervention compared to baseline measurements.

    Time frame: 4 Weeks

Study contacts

Contact information is provided by the study sponsor or research team.

Michel Hochuli, MD, PhD

CONTACT

[email protected]

+41 31 664 03 18

Sponsors and collaborators

Lead sponsor

Insel Gruppe AG, University Hospital Bern

Other

Collaborators

  • Medical University Innsbruck
  • University Hospital Freiburg
  • University Hospital Heidelberg
  • University of Zurich

Registry information

Official study title

Dietary Treatment Strategies and Metabolic Control in Glycogen Storage Disease Type I (GSD-DIET)

Acronym: GSD-DIET

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Feb 28, 2025
Registry last updated
May 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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