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

May 7, 2026 updated by: Insel Gruppe AG, University Hospital Bern

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

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

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.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Switzerland
      • Bern, Switzerland, 3010
        • Recruiting
        • Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital
        • Contact:
          • Michel Hochuli, MD, PhD
      • Zurich, Switzerland, 8091
        • Not yet recruiting
        • Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Diet with additional fructose intake
Dietary supplement: Fructose
40g fructose (free and bound, max amount of fructose from added free sugar/saccharose 25g)
Experimental: Diet with additional fructose and galactose intake
Dietary supplement: Fructose and galactose
10g galactose (mostly from lactose) plus 40g of fructose (free and bound, max amount of fructose from added free sugar/saccharose 25g)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
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.
4 Weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
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
4 Weeks
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
4 Weeks
Plasma metabolite changes in targeted metabolomics during the dietary intervention compared to baseline measurements.
Time Frame: 4 Weeks
4 Weeks
Plasma metabolite changes in targeted lipidomics during the dietary intervention compared to baseline measurements.
Time Frame: 4 Weeks
4 Weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Insel Gruppe AG, University Hospital Bern

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Zurich
University Hospital Heidelberg
Medical University Innsbruck
University Hospital Freiburg

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Michel Hochuli, MD, PhD, Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 24, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 24, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 24, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 28, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 7, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2024-02154

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Individual participant data (IPD) will be made available upon reasonable request to the principal investigator.

IPD Sharing Time Frame

IPD will be made available starting 12 months after publication of trial results.

IPD Sharing Access Criteria

Ethics approval, as applicable under Swiss legislation, will need to be obtained by those requesting the data. Additionally, a data transfer and processing agreement must be in place to ensure compliance with data protection regulations.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ANALYTIC_CODE

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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