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

Trial Summary

What is the purpose of this trial?

The goal of this basic science clinical trial is to understand whether adipose tissue blood flow changes between younger and older healthy adults. The main question\[s\] it aims to answer are: * Is basal and nutrient responsive adipose tissue blood flow (ATBF) different between younger and older adults * What molecular and systemic signatures related to adipose tissue blood flow are altered between these two groups. Participants will undergo measurements of adipose tissue blood flow using the xenon washout technique, undergo 2 abdominal subcutaneous adipose tissue biopsies, and drink a sugary drink.

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 data supports the effectiveness of the treatment 75 gm oral glucose load for studying fat tissue blood flow in aging?

The 75 gm oral glucose tolerance test (OGTT) is commonly used to assess glucose metabolism and predict the risk of diabetes or glucose metabolism disorders, which can indirectly relate to changes in blood flow and tissue health. This test provides important information about how the body processes sugar, which may help understand changes in fat tissue blood flow as people age. ^{1 2 3 4 5}

Is the oral glucose tolerance test (OGTT) generally safe for humans?

The oral glucose tolerance test (OGTT), which involves a 75-gram glucose load, is widely used and considered safe for assessing glucose metabolism in humans. It is a standard procedure for evaluating how the body processes sugar and is used globally without significant safety concerns. ^{1 2 3 5 6}

How does the glucose load test differ from other treatments for studying fat tissue blood flow in aging?

The glucose load test is unique because it involves administering a specific amount of glucose to observe its effects on blood flow in fat tissue, particularly in the context of aging. Unlike other treatments that might focus on direct interventions, this test helps understand how glucose impacts blood flow and vascular function, which can be different in older adults compared to younger individuals. ^{4 7 8 9 10}

Research Team

Kelli Lytle, PhD

Principal Investigator

Mayo Clinic

Eligibility Criteria

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

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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]

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]

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 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]

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 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]

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 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]

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]

References

1. Canada pubmed.ncbi.nlm.nih.gov

Prediction of Glucose Metabolism Disorder Risk Using a Machine Learning Algorithm: Pilot Study. [2020]

2. Ireland pubmed.ncbi.nlm.nih.gov

Body surface area and glucose tolerance - The smaller the person, the greater the 2-hour plasma glucose. [2022]

3. United States pubmed.ncbi.nlm.nih.gov

Assessing the shape of the glucose curve during an oral glucose tolerance test. [2022]

4. Korea (South) 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. [2022]

5. United States 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. [2019]

6. United States pubmed.ncbi.nlm.nih.gov

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

7. United States pubmed.ncbi.nlm.nih.gov

Reduction of Central Blood Pressure in Response to Oral Glucose Loading Is Blunted in Patients With Diabetes Mellitus. [2016]

8. England pubmed.ncbi.nlm.nih.gov

Postchallenge glucose rises with increasing age even when glucose tolerance is normal. [2007]

9. England pubmed.ncbi.nlm.nih.gov

Lack of effect of oral glucose loading on conduit vessel endothelial function in healthy subjects. [2022]

10. United States 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. [2022]