Oral Galactose as a Substrate for Post-Exercise Skeletal Muscle Glycogen Repletion in Individuals With Type 1 Diabetes
This Ph.D. project investigates whether orally ingested galactose can be taken up by skeletal muscle and the heart in response to exercise or hyperinsulinemia, and whether it may serve as a viable nutritional strategy for individuals with type 1 diabetes (T1D).
Although exercise provides significant health benefits for people with T1D, it is often associated with substantial glucose fluctuations and an increased risk of hypoglycemia. Conventional carbohydrate strategies based on glucose may further exacerbate glycemic instability due to the rapid increase in blood glucose levels. In contrast, galactose is metabolized more slowly and may therefore provide a more stable energy source during and after exercise.
Previous research has demonstrated that intravenously administered galactose is taken up by human skeletal muscle, with uptake increasing during exercise, suggesting a mechanism that may be at least partly insulin-independent. Building on these findings, this project aims to determine whether similar uptake occurs when galactose is ingested orally.
This study uses a randomized controlled design and applies non-invasive 18F-FDGal PET imaging to quantify galactose uptake in skeletal muscle and cardiac tissue. The findings may contribute to improving dietary recommendations for individuals with T1D, particularly in relation to maintaining stable blood glucose levels during and after physical activity.
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Previous studies using intravenously administered galactose have demonstrated direct uptake by human skeletal muscle, with uptake increasing following exercise. These findings challenge the traditional view that galactose must first be converted to glucose in the liver before utilization by peripheral tissues and suggest that exercise may stimulate galactose uptake through partly insulin-independent mechanisms. However, it remains unknown whether the tissue distribution and uptake kinetics of orally ingested galactose resemble those observed during intravenous administration.
The primary hypothesis is that prior exercise increases skeletal muscle galactose uptake. A secondary hypothesis is that co-ingestion of glucose reduces peripheral galactose uptake, potentially through increased hepatic extraction.
To investigate this, eight healthy participants and eight individuals with T1D will complete two study days in a randomized crossover design. On each study day, participants will perform 30 minutes of unilateral high-intensity leg exercise, with the non-exercised leg serving as an intra-individual control.
Following exercise, participants will ingest either 30 g galactose or 30 g galactose combined with 30 g glucose together with 100 MBq of ¹⁸F-FDGal. A 90-minute dynamic whole-body PET scan will be performed to characterize the tissue distribution and kinetics of ¹⁸F-FDGal, followed by a static brain scan. Tissue-specific time-activity curves will be extracted and, together with serial blood sampling, used for kinetic modeling of galactose uptake in skeletal muscle, liver, heart, and brain. Blood samples will be collected throughout the experiment to characterize systemic metabolic responses.
The unilateral exercise model enables direct within-participant comparison of galactose uptake between exercised and resting skeletal muscle, while the crossover design allows assessment of how glucose co-ingestion affects galactose distribution and uptake.
Study Type
Enrollment (Estimated)
Phase
- Not Applicable
Contacts and Locations
Study Contact
- Name: Ole Fuglsang-Jensen, master in sports science
- Phone Number: +4527897650
- Email: AU664914@uni.au.dk
Study Locations
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Aarhus, Denmark, 8000
- steno diabetes center Aarhus
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Contact:
- Esben Søndergaard, Professor
- Phone Number: +45
- Email: esbensoe@rm.dk
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Aarhus, Denmark, 8000
- Aarhus Universitet
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Contact:
- Ole Fuglsang-Jensen
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
Description
Inclusion Criteria:
- Healthy or T1D
- BMI 18,5-30 kg/m2
- Singed informed consent
Exclusion Criteria:
- Clinically significant heart, lung, kidney, liver, endocrine, or malignant disease based on information collected during the initial screening visit as well as blood tests
- Lack of awareness of hypoglycemia episodes
- Blood donation within the last 3 months
- Smoking
- Alcohol or substance abuse
- Participation in other studies involving ionizing radiation within the last 6 months
- Claustrophobia
- Inability to train one leg for one hour
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Prevention
- Allocation: Randomized
- Interventional Model: Crossover Assignment
- Masking: Single
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
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Experimental: Galactose
The patient will orally ingest 30 g of galactose.
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Participants undergo two experimental conditions in a randomized crossover design.
In one condition, participants ingest 30 g of galactose, whereas in the other condition, they ingest 30 g of galactose combined with 30 g of glucose.
The order of the conditions is randomized across participants.
Other Names:
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Active Comparator: Galactose + Glucose
The patient will orally ingest 30 g of galactose and 30 g of glucose.
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Participants undergo two experimental conditions in a randomized crossover design.
In one condition, participants ingest 30 g of galactose, whereas in the other condition, they ingest 30 g of galactose combined with 30 g of glucose.
The order of the conditions is randomized across participants.
Other Names:
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Time Frame |
|---|---|
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Skeletal muscle galactose uptake rate (μmol/min/g) measured by 2-(18)F-fluoro-2-deoxy-d-galactose (18F-FDGal)
Time Frame: Measurement will be made on each of the two study days
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Measurement will be made on each of the two study days
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Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
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Hepatic galactose uptake
Time Frame: Measurements will be made on each of the two study days
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Hepatic galactose uptake rate (μmol/min/g) measured by 2-(18)F-fluoro-2-deoxy-d-galactose (18F-FDGal)
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Measurements will be made on each of the two study days
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Cerebral galactose Uptake
Time Frame: Measurement will be made on each of the two study days
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Galactose uptake in the brain, measured by a 10-minute static PET-CT scan performed after the 90-minute dynamic scan.
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Measurement will be made on each of the two study days
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Collaborators and Investigators
Sponsor
Study record dates
Study Major Dates
Study Start (Estimated)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- 1-10-72-25-26 (Other Identifier: Research Ethics Committee Denmark)
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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