Glucose MetabolismNCT03851744
High Altitude and Exogenous Carbohydrate Oxidation
A study testing Sea Level and High Altitude in people with Glucose Metabolism and High Altitude, run by United States Army Research Institute of Environmental Medicine at 1 site in United States.
Trial summary
Recent studies have reported that oxidation of exogenous carbohydrate is reduced under acute hypobaric hypoxic (high altitude; HA) conditions compared to normoxia (sea level; SL) in native lowlanders. However, the mechanisms by which HA suppresses exogenous carbohydrate oxidation are not known. Read more about this study
- Who is it for?
- Ages 18 to 39 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Glucose Metabolism, High Altitude
- What is being tested?
- Sea Level and High Altitude
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 10 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Nov 2018to 1 Sep 2020
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 39 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Men aged 18 - 39 years
- Born at altitudes less than 2,100 m (~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.)
- Physically active based on assessment of physical activity history (2-4 days per week aerobic and/or resistance exercise)
- Have supervisor approval (permanent party military and civilians)
- Willing to refrain from alcohol, smokeless nicotine products and dietary supplement use during study periods
- Refrain from taking any nonsteroidal anti-inflammatory drugs (NSAIDs; e.g. aspirin, Advil®, Aleve®, Naprosyn®, or any aspirin-containing product) for 10 days before and at least 5 days AFTER each muscle biopsy. (*Tylenol® or acetaminophen is ok to use if needed for discomfort)
Who cannot join
- Born at altitudes greater than 2,100 m (~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.)
- Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months (Examples include Ft. Huachuca, Arizona; Lima, Peru; Feldberg, Germany, Etc.)
- Musculoskeletal injuries that compromise exercise capability
- Metabolic or cardiovascular abnormalities (determined by resting ECG), gastrointestinal disorders (e.g., kidney disease, diabetes, cardiovascular disease, etc.)
- Medication that affects macronutrient metabolism (i.e., diabetes medications, statins, corticosteroids, etc) and/or the ability to participate in strenuous exercise
- Evidence of apnea or other sleeping disorders
Show all 17Show fewer
- Prior diagnosis of high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE)
- Presence of asthma or respiratory tract infections (< 1 month prior)
- Allergies or intolerance to foods (including but not limited to lactose intolerance/milk allergy), vegetarian practices, or medications (including, but not limited to, lidocaine ) to be utilized in the study
- Smoking or vaping
- History of complications with lidocaine
- Taking medications that interfere with oxygen delivery and transport (Includes sedatives, sleeping aids, tranquilizers and/or any medication that depresses ventilation, diuretics, alpha and beta blockers)
- Evidence of any physical, mental, and/or medical conditions that would make the proposed studies relatively more hazardous as determined by the Office of Medical Support and Oversight
- Present condition of alcoholism, anabolic steroids, or other substance abuse issues
- Anemia (hematocrit <38% and hemoglobin <12.5 g/dL) and Sickle Cell Anemia/Trait
- Abnormal prothrombin time (PT)/ partial thromboplastin time (PTT) test or problems with blood clotting
- Blood donation within 8 weeks of beginning the study
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Mechanistic Effects of Acute Hypobaric Hypoxia on Exogenous Carbohydrate Utilization During Steady-state Aerobic Exercise
Recent studies have reported that oxidation of exogenous carbohydrate is reduced under acute hypobaric hypoxic (high altitude; HA) conditions compared to normoxia (sea level; SL) in native lowlanders. However, the mechanisms by which HA suppresses exogenous carbohydrate oxidation are not known. This study will seek to confirm that acute HA exposure decreases exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL, and explore if the mechanism inhibiting plasma glucose uptake is insulin dependent or independent.
Read the detailed description
This randomized crossover study will examine substrate metabolic responses to ingesting supplemental carbohydrate during steady-state aerobic-type exercise at sea level (SL) and following acute (~5 h) exposure to HA (4,300 m) conditions in 10 healthy, recreationally active adults between the ages of 18-39 yrs. Following a 48-hr muscle glycogen normalization period, volunteers will complete 80-min of metabolically-matched, steady-state aerobic exercise on a treadmill, and consume 145 g of glucose (1.8 g·min-1) at SL and HA. Treadmill exercise will be performed at the same absolute workload, with speed and grade being the same at SL and HA to induce the same absolute workload between phases. SL and HA trials will occur in the US Army Research Institute of Environmental Medicine (USARIEM) hypobaric chamber and will be separated by a minimum 7-d washout period between each protocol day. 6-6-[2H2] glucose will be used as a tracer to assess glucose turnover. Indirect calorimetry, breath sampling for 13C/12C expired in CO2, and urine collections will be used to determine carbohydrate, fat, and protein oxidation during exercise at SL and HA. Serial blood draws will be collected during each trial to assess endocrine and circulating substrate responses to exercise, carbohydrate, and hypoxia. Muscle biopsies will be collected before and after steady-state exercise to examine intramuscular glucose transport expression and translocation, glycogen status, and activity enzyme intermediates in aerobic and anaerobic energy metabolism.
- Conditions
- Glucose Metabolism, High Altitude
- Being tested
- Sea Level, High Altitude
- Medical subject headings
- Altitude Sickness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sea LevelOther
Carbohydrate consumed at 1.8 g/min during treadmill exercise at SL
High AltitudeOther
Carbohydrate consumed at 1.8 g/min during treadmill exercise at HA
| Study group | Role | What they receive |
|---|---|---|
| Sea Level | Active comparator | Carbohydrate metabolism measured at SL Receives: Other: Sea Level |
| High Altitude | Experimental | Carbohydrate metabolism measured at HA Receives: Other: High Altitude |
What is being measured
The primary outcome is the main question the study is designed to answer.
Rate of Exogenous Carbohydrate Oxidation
Use indirect calorimetry and stable isotope methodologies to measure if acute HA exposure changes the rate of exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL
Measured: 7 hours
Rate of Glucose Turnover
Use stable isotope methodologies to measure if acute HA exposure changes the rate of glucose turnover during steady-state aerobic exercise compared to SL
Measured: 7 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Feb 2019
- Study start28 Nov 2018
- Primary completion1 Nov 2019
- Study completion1 Sep 2020
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Glucose MetabolismStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 10 participants (actual)
Sponsor and investigators
- Lead sponsor
- United States Army Research Institute of Environmental Medicine
- Sponsor type
- US federal agency
- Collaborators
- University of Arkansas
- Responsible party
- Sponsor
- Investigators
- Lee M Margolis, PhD, Principal investigator, Military Nutrition Division, USARIEM
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03851744
- Sponsor's protocol ID
- 18-09HC
- Status last verified
- Aug 2021
- First submitted
- 30 Aug 2018
- Last updated
- 2 Sep 2021
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Sep 2021. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Mechanistic Effects of Acute Hypobaric Hypoxia on Exogenous Carbohydrate Utilization During Steady-state Aerobic Exercise
- ClinicalTrials.gov ID
- NCT03851744
- Acronym / sponsor ID
- 18-09HC
- Conditions
- Glucose Metabolism, High Altitude
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 10 participants (actual)
- Lead sponsor
- United States Army Research Institute of Environmental MedicineUS federal agency
- Collaborators
- University of Arkansas
- Study start
- 28 Nov 2018 (actual)
- Primary completion
- 1 Nov 2019 (actual)
- Study completion
- 1 Sep 2020 (actual)
- First posted
- 22 Feb 2019 (actual)
- Results
- Posted 2 Sep 2021
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Recent studies have reported that oxidation of exogenous carbohydrate is reduced under acute hypobaric hypoxic (high altitude; HA) conditions compared to normoxia (sea level; SL) in native lowlanders. However, the mechanisms by which HA suppresses exogenous carbohydrate oxidation are not known. This study will seek to confirm that acute HA exposure decreases exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL, and explore if the mechanism inhibiting plasma glucose uptake is insulin dependent or independent.
Detailed description
This randomized crossover study will examine substrate metabolic responses to ingesting supplemental carbohydrate during steady-state aerobic-type exercise at sea level (SL) and following acute (~5 h) exposure to HA (4,300 m) conditions in 10 healthy, recreationally active adults between the ages of 18-39 yrs. Following a 48-hr muscle glycogen normalization period, volunteers will complete 80-min of metabolically-matched, steady-state aerobic exercise on a treadmill, and consume 145 g of glucose (1.8 g·min-1) at SL and HA. Treadmill exercise will be performed at the same absolute workload, with speed and grade being the same at SL and HA to induce the same absolute workload between phases. SL and HA trials will occur in the US Army Research Institute of Environmental Medicine (USARIEM) hypobaric chamber and will be separated by a minimum 7-d washout period between each protocol day. 6-6-[2H2] glucose will be used as a tracer to assess glucose turnover. Indirect calorimetry, breath sampling for 13C/12C expired in CO2, and urine collections will be used to determine carbohydrate, fat, and protein oxidation during exercise at SL and HA. Serial blood draws will be collected during each trial to assess endocrine and circulating substrate responses to exercise, carbohydrate, and hypoxia. Muscle biopsies will be collected before and after steady-state exercise to examine intramuscular glucose transport expression and translocation, glycogen status, and activity enzyme intermediates in aerobic and anaerobic energy metabolism.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Sea Level | Active comparator | Other: Sea LevelCarbohydrate metabolism measured at SL |
| High Altitude | Experimental | Other: High AltitudeCarbohydrate metabolism measured at HA |
Who may qualify
- Ages
- 18 to 39 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Men aged 18 - 39 years
- Born at altitudes less than 2,100 m (~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.)
- Physically active based on assessment of physical activity history (2-4 days per week aerobic and/or resistance exercise)
- Have supervisor approval (permanent party military and civilians)
- Willing to refrain from alcohol, smokeless nicotine products and dietary supplement use during study periods
Key exclusion criteria (17 listed)
- Born at altitudes greater than 2,100 m (~7,000 feet; Examples include Santa Fe, New Mexico; Laramie, Wyoming; Etc.)
- Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months (Examples include Ft. Huachuca, Arizona; Lima, Peru; Feldberg, Germany, Etc.)
- Musculoskeletal injuries that compromise exercise capability
- Metabolic or cardiovascular abnormalities (determined by resting ECG), gastrointestinal disorders (e.g., kidney disease, diabetes, cardiovascular disease, etc.)
- Medication that affects macronutrient metabolism (i.e., diabetes medications, statins, corticosteroids, etc) and/or the ability to participate in strenuous exercise
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Sea LevelCarbohydrate consumed at 1.8 g/min during treadmill exercise at SL | Other | Sea Level |
| High AltitudeCarbohydrate consumed at 1.8 g/min during treadmill exercise at HA | Other | High Altitude |
Primary outcome
Rate of Exogenous Carbohydrate Oxidation
Time frame: 7 hours
Use indirect calorimetry and stable isotope methodologies to measure if acute HA exposure changes the rate of exogenous carbohydrate oxidation during steady-state aerobic exercise compared to SL
Rate of Glucose Turnover
Time frame: 7 hours
Use stable isotope methodologies to measure if acute HA exposure changes the rate of glucose turnover during steady-state aerobic exercise compared to SL
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Sep 2021.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Lee M Margolis, PhD principal investigator
Military Nutrition Division, USARIEM
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Sea Level and High Altitude in people with Glucose Metabolism and High Altitude, run by United States Army Research Institute of Environmental Medicine at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 2 Sep 2021. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 2 Sep 2021). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Rate of Exogenous Carbohydrate Oxidation (time frame: 7 hours). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Sep 2021; AzTrials last refreshed its copy on 30 Oct 2026.