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

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: Recruiting
• Conditions: Glycogen Storage Disease Type I
• Intervention / Treatment: Dietary supplement: Fructose; Dietary supplement: Fructose and galactose

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: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Michel Hochuli, MD, PhD; Phone Number: +41 31 664 03 18; Email: michel.hochuli@insel.ch

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: Laura Horka, MD; Phone Number: +41 44 255 36 20; Email: laura.horka@usz.ch

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Change in lactate during the dietary intervention compared to baseline under the usual diet	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

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

Collaborators and Investigators

• Sponsor: Insel Gruppe AG, University Hospital Bern
• Collaborators: University of Zurich; University Hospital Heidelberg; Medical University Innsbruck; University Hospital Freiburg
• Investigators: Principal Investigator: Michel Hochuli, MD, PhD, Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism

Study record dates

Study Major Dates

• Study Start (Actual): April 24, 2025
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: February 24, 2025
• First Submitted That Met QC Criteria: February 24, 2025
• First Posted (Actual): February 28, 2025

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Fructose; Metabolism; Galactose; Gsd1
• Additional Relevant MeSH Terms: Metabolism, Inborn Errors; Genetic Diseases, Inborn; Metabolic Diseases; Carbohydrate Metabolism, Inborn Errors; Glycogen Storage Disease; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Nutritional and Metabolic Diseases; Glycogen Storage Disease Type I; Carbohydrates; Sugars; Hexoses; Monosaccharides; Ketoses; Galactose; Fructose
• Other Study ID 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