Glucose Load Test for Studying Fat Tissue Blood Flow in Aging

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Mayo Clinic

Must not be taking: Anticoagulants, Statins, Antipsychotics, others

Disqualifiers: Cardiometabolic diseases, Pregnant, Smokers, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

24 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how blood flow in fat tissue differs between younger and older adults. Researchers seek to determine if blood flow changes when the body is at rest and after consuming a sugary drink (75 gm oral glucose load). Participants will have small fat tissue samples taken from their abdomen and will drink a glucose solution. Healthy, non-smoking individuals aged 18-35 or 65-80 years, with a BMI (a measure of body fat based on height and weight) between 20-25, are ideal candidates for the trial. As an unphased study, this trial offers participants the opportunity to contribute to valuable research on age-related changes in blood flow.

Will I have to stop taking my current medications?

If you are taking prescription anticoagulants or medications that affect fat tissue metabolism, like statins or fish oil, you will need to stop taking them to participate in this trial.

What prior data suggests that the glucose load test is safe for studying fat tissue blood flow?

Research has shown that the 75-gram oral glucose load is generally safe for people. This method is often used in glucose tolerance tests to help doctors assess how well the body handles sugar. During these tests, participants drink a sugary solution, and doctors monitor changes in blood sugar levels over time.

In past studies, most people have tolerated this glucose load well, experiencing few side effects. The main purpose is to observe how the body moves sugar from the blood into tissues like muscle and fat. This is a common practice and is not known to harm healthy individuals. However, some people might experience minor issues like dizziness or nausea, though these are rare.

Overall, the oral glucose load is a well-understood and safe method for studying how the body processes sugar. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it aims to uncover how glucose affects blood flow in fat tissue as people age. While the standard approaches focus on blood sugar levels and metabolic health, this study looks into the specific changes in blood flow dynamics in fat tissue, which is less explored. By understanding these changes, the study could reveal new insights into aging and metabolic health, potentially leading to innovative strategies for managing age-related conditions.

What evidence suggests that this glucose load test is effective for studying fat tissue blood flow in aging?

In this trial, participants will receive a 75-gram oral glucose load to study how the body handles sugar. Research shows that this test helps determine how well insulin, the hormone controlling blood sugar, functions and can reveal differences in sugar processing across age groups. Previous research found that older adults may handle glucose differently than younger adults. This test observes the body's reaction to sugar and measures glucose tolerance, indicating how well the body manages sugar levels after eating. Although this trial does not focus on treatment effectiveness, the glucose load aids in understanding changes in blood flow to fat tissue, which might vary with age. ^{1 6 7 8 9}

Who Is on the Research Team?

Kelli Lytle, PhD

Principal Investigator

Mayo Clinic

Are You a Good Fit for This Trial?

This trial is for healthy adults aged 18-35 or 65-80 with a BMI of 20-25. It's not for those with heart disease, diabetes, high blood pressure, on certain meds affecting fat metabolism (like statins), pregnant/nursing women, smokers, or anyone unable to consent.

Inclusion Criteria

Your body mass index (BMI) should be between 20 and 25.

Exclusion Criteria

I have been diagnosed with a heart or metabolic condition like diabetes or high blood pressure.

I am taking medication or supplements that affect fat metabolism.

I am on prescription blood thinners.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

1 visit (in-person)

Baseline Assessment

Participants undergo baseline assessments including informed consent, pregnancy test, DEXA scan, baseline labs, and cardiopulmonary exercise test

1 day

1 visit (in-person)

Intervention

Participants undergo adipose tissue blood flow measurements using the xenon washout technique, adipose tissue biopsies, and consume a sugary drink

1 day

1 visit (in-person)

Follow-up

Participants are monitored for any immediate post-intervention effects and data collection

1-2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• 75 gm oral glucose load

Trial Overview

The study investigates how blood flow in fatty tissue differs between younger and older adults by using the xenon washout technique after participants drink a sugary solution. It also looks at molecular changes related to this blood flow.

How Is the Trial Designed?

Group I: Older Adults Experimental Treatment 1 Intervention

Group II: Younger Adults Active Control 1 Intervention

Who Is Running the Clinical Trial?

Mayo Clinic

Lead Sponsor

Trials

3,427

Recruited

3,221,000+

National Center for Advancing Translational Sciences (NCATS)

Collaborator

Trials

394

Recruited

404,000+

Published Research Related to This Trial

In a study of 39 healthy non-diabetic subjects, an oral glucose tolerance test (OGTT) significantly increased blood glucose and insulin levels compared to baseline, indicating a normal physiological response to glucose intake.

Despite these increases in glucose and insulin, there was no significant change in vascular function, suggesting that short-term elevations in these levels do not impair arterial function in healthy individuals.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Lack of effect of oral glucose loading on conduit vessel endothelial function in healthy subjects. Siafarikas, A., Watts, K., Beye, P., et al.[2022]

Elderly women with hypertension and diabetes have significantly higher blood glucose levels after a 75 g oral glucose tolerance test (OGTT) compared to those with hypertension alone, indicating impaired glucose control.

Unlike those with only hypertension, women with both hypertension and diabetes did not experience changes in arterial stiffness or blood pressure after the OGTT, suggesting potential issues with vascular function in this group.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of oral glucose tolerance testing on changes in arterial stiffness and blood pressure in elderly women with hypertension and relationships between the stage of diabetes and physical fitness levels. Lee, J., Park, W., Sung, E., et al.[2022]

In a study of 2659 individuals aged 45 to 70 at increased cardiovascular risk, it was found that smaller body surface area (BSA) is associated with higher 2-hour postload plasma glucose (2hPG) levels during an oral glucose tolerance test (OGTT), indicating that body size significantly affects glucose tolerance results.

Smaller individuals are more likely to be diagnosed with glucose intolerance or type 2 diabetes based on OGTT results, suggesting that the standardized glucose load may lead to misdiagnosis in people of different body sizes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Body surface area and glucose tolerance - The smaller the person, the greater the 2-hour plasma glucose. Palmu, S., Rehunen, S., Kautiainen, H., et al.[2022]

A new method for the oral glucose tolerance test (OGTT) was developed that allows for more accurate predictions of glucose levels by plotting data points at their actual collection times, improving the test's reproducibility.

In clinical trials with two groups of patients, this method successfully identified various glucose tolerance statuses, including five cases of impaired glucose tolerance and one case of gestational diabetes, demonstrating its efficacy in diagnosing diabetes risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Proportional versus projected glucose tolerance values: a quality control program. Crawford, JF.[2019]

In a study of 2591 subjects with normal glucose tolerance, it was found that for every 10-year increase in age, there was a significant rise of 0.20 mmol/l in glucose levels one hour after an oral glucose tolerance test (OGTT).

The increase in glucose levels with age was more pronounced in men compared to women, suggesting that aging may affect glucose metabolism differently based on gender, which could have implications for cardiovascular disease risk even in individuals without diabetes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Postchallenge glucose rises with increasing age even when glucose tolerance is normal. Rhee, MK., Ziemer, DC., Kolm, P., et al.[2007]

In a study of 926 individuals, 39% of those with normal glucose tolerance (NGT) had a 1-hour OGTT glucose level greater than 155 mg/dL, indicating a higher risk for developing type 2 diabetes (T2DM) and cardiovascular disease.

Subjects with NGT and a 1-hour OGTT glucose >155 mg/dL exhibited lower insulin sensitivity and impaired β-cell function, along with worse cardiovascular risk factors, compared to those with lower glucose levels, highlighting the need for monitoring and potential intervention.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Elevated 1-hour postload plasma glucose levels identify subjects with normal glucose tolerance but impaired β-cell function, insulin resistance, and worse cardiovascular risk profile: the GENFIEV study. Bianchi, C., Miccoli, R., Trombetta, M., et al.[2022]

In a study of 85 patients with slightly impaired glucose tolerance, the difference in plasma glucose levels after a 100-gm glucose load compared to a 50-gm load was significantly larger (54 mg/dl) than previously reported for normal subjects, indicating that the loading dose affects test outcomes more than previously thought.

The study suggests that patients with impaired glucose tolerance respond differently to varying glucose doses compared to normal subjects, making it inappropriate to compare OGTT results across different loading doses or to use conversion formulas between them.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The size of the loading dose as an important determinant of the results of the oral glucose tolerance test: a study in subjects with slightly impaired glucose tolerance. de Nobel, E., van't Laar, A.[2019]

In a study of 551 subjects, the shape of the plasma glucose response during an oral glucose tolerance test (OGTT) was found to vary based on glucose tolerance status and sex, with biphasic responses indicating better metabolic health compared to monophasic responses.

The study suggests that the 'shape index' of glucose response could serve as a valuable screening tool for assessing metabolic health and understanding genetic influences on glucose tolerance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Assessing the shape of the glucose curve during an oral glucose tolerance test. Tschritter, O., Fritsche, A., Shirkavand, F., et al.[2022]

In a study of 85 patients with coronary artery disease, glucose loading significantly reduced central systolic blood pressure and the augmentation index, indicating improved central hemodynamics after eating, particularly in those with normal or impaired glucose tolerance.

However, patients with diabetes mellitus showed a blunted response to glucose loading, suggesting that their ability to benefit from this effect is impaired compared to those with normal glucose tolerance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Reduction of Central Blood Pressure in Response to Oral Glucose Loading Is Blunted in Patients With Diabetes Mellitus. Higaki, T., Kurisu, S., Watanabe, N., et al.[2016]

A machine learning model called XGBoost demonstrated superior accuracy in predicting the risk of developing diabetes or glucose metabolism disorders (GMD) compared to traditional logistic regression methods, based on analysis of 13,581 and 6,760 oral glucose tolerance tests (OGTTs).

Including complete OGTT data significantly improved prediction accuracy, highlighting the importance of comprehensive glucose metabolism information for early detection of diabetes and GMD.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prediction of Glucose Metabolism Disorder Risk Using a Machine Learning Algorithm: Pilot Study. Maeta, K., Nishiyama, Y., Fujibayashi, K., et al.[2020]

Citations

1.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC6205735/

Age-related Changes in Glucose Metabolism, Hyperglycemia ...

We review the current knowledge of age-related changes in glucose metabolism, present data on hyperglycemia as a risk factor for CVD, and we attempt to ...

2.

ncbi.nlm.nih.gov

ncbi.nlm.nih.gov/books/NBK555976/

Blood Glucose Monitoring - StatPearls - NCBI Bookshelf - NIH

Oral glucose tolerance test: Glucose tolerance range at two hours post 75-gram oral glucose ingestion: ≥11.1 mmol/L, or ≥200 mg/dL. A ...

3.

sciencedirect.com

sciencedirect.com/science/article/pii/S0026049519300861

The incretin system in healthy humans: The role of GIP and ...

Insulin, C-peptide and glucose responses from experiments in 17 healthy but overweight/obese subjects given an oral glucose tolerance test (75 g) at time 0 on 4 ...

4.

clinicaltrials.gov

clinicaltrials.gov/study/NCT04300049

Effect of Physiologic Hyperglucogonemia on Adipocyte ...

Subjects then will have a 75 gram oral glucose tolerance test to document the presence of normal glucose tolerance. Blood will be drawn at -30, -15, 0 and ...

5.

mdpi.com

mdpi.com/2072-6643/12/10/2979

Obese Older Type 2 Diabetes Mellitus Patients with Muscle ...

An oral glucose tolerance test was used to calculate indices representing organ insulin resistance (muscle, liver, and adipose tissue) and β- ...

6.

medlineplus.gov

medlineplus.gov/ency/article/003466.htm

Glucose tolerance test - non-pregnant

The glucose tolerance test is a lab test to check how your body moves sugar from the blood into tissues like muscle and fat.

7.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC9686143/

Oral glucose tolerance test: how to maximize its diagnostic ...

For OGTT, at least two blood samples (0 min and 120 min) are needed to characterize carbohydrate tolerance (12). The OGTT results are used to classify subjects ...

8.

diabetesjournals.org

diabetesjournals.org/care/article/48/Supplement_1/S27/157566/2-Diagnosis-and-Classification-of-Diabetes

2. Diagnosis and Classification of Diabetes: Standards of Care ...

Plasma glucose criteria include either the fasting plasma glucose (FPG), 2-h plasma glucose (2-h PG) during a 75-g oral glucose tolerance test ( ...

9.

ahajournals.org

ahajournals.org/doi/10.1161/CIRCRESAHA.118.312806?gh_jid=6279921003

Age-Related Changes in Glucose Metabolism ...

We review the current knowledge of age-related changes in glucose metabolism, present data on hyperglycemia as a risk factor for CVD, and we attempt to ...