Study of Fat Tissue's Ability to Take up Sugar in the Obese Population

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

ACTIVE_NOT_RECRUITING

Total Enrollment

90 participants

Study Classification

OBSERVATIONAL

Study Start Date

2017-07-01

Study Completion Date

2027-01-31

Brief Summary

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People who are obese often have insulin resistance (inability of insulin to properly control blood sugar) and high blood sugar. However, not all people with obesity have this problem. About one-third of people with obesity have normal sugar metabolism (the way your body uses sugar). Similarly, not all people who are lean are also metabolically healthy and a subset of people who are lean are referred to as metabolically abnormal lean (MAL) or metabolically obese lean because they have the abnormalities in glucose metabolism typically associated with obesity. The reasons why some people with obesity have a problem with blood sugar control and others do not are not entirely clear. It is thought that impaired muscle sugar uptake is the main problem related to high blood sugar in people with obesity. However, adipose tissue (fat tissue) also consumes a substantial amount of blood sugar. Therefore, it is unclear whether muscle or adipose tissue (fat tissue) are primarily responsible for altered blood sugar concentrations in persons with metabolically abnormal obesity (MAO) (those with insulin resistance), compared to those with metabolically normal (healthy) obesity (MNO), or whether "healthy" adipose tissue (fat tissue) expansion in MNO people compared with lean people provides a vessel for blood sugar removal that helps maintain normal blood sugar concentration.

Accordingly, the investigators will determine the amount of sugar that is taken up by the body and in the cells of adipose tissue (fat tissue) and muscle by infusing labeled sugar into the blood and looking at its disappearance from blood and appearance in adipose tissue (fat tissue) and muscle. The investigators will also determine how well insulin, a hormone that controls blood sugar, turns on signals that stimulate sugar uptake in fat and muscle cells. These studies will be done after an overnight fast and during an infusion of sugar and insulin (hyperinsulinemic-euglycemic clamp), in sex- and age-matched people who are insulin resistant and insulin sensitive. People with obesity will also be invited to complete a \~10% diet-induced weight loss program and will be studied again after they have achieved the weight loss goal. A group of sex- and age-matched metabolically normal lean participants will serve as control group. An attempt will be made to also study a group of sex- and age-matched metabolically abnormal lean participants.

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Detailed Description

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Conditions

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Glucose Metabolism Disorders

Study Design

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Observational Model Type

COHORT

Study Time Perspective

CROSS_SECTIONAL

Study Groups

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Metabolically Normal Obese (likely insulin sensitive)

i) BMI ≥30.0 but \<45.0 kg/m2; maximum body circumference \<165 cm to ensure subjects fit into the PET/CT and MR scanners; iii) fasting blood glucose: \<100 mg/dl; iv) blood glucose 2 h after an OGTT: \<140 mg/dl; v) HbA1c \<5.7 %; vi) fasting insulin: \<20 µU/mL.

Weight Loss

Intervention Type OTHER

Diet-induced weight loss (obese only)

Metabolically Abnormal Obese (likely insulin resistant)

i) BMI ≥30.0 but \<45.0 kg/m2; maximum body circumference \<165 cm to ensure subjects fit into the PET/CT and MR scanners; iii) fasting blood glucose: ≥100 mg/dl or blood glucose 2 h after an OGTT: ≥140 or fasting insulin: \>20 µU/mL.

Weight Loss

Intervention Type OTHER

Diet-induced weight loss (obese only)

Metabolically Normal Lean

i) BMI ≥18.5 but \<25.0 kg/m2; ii) maximum body circumference \<165 cm to ensure subjects fit into the PET/CT and MR scanners; iii) fasting blood glucose: \<100 mg/dl; iv) blood glucose 2 h after an OGTT: \<140 mg/dl; v) HbA1c \<5.7 %; vi) fasting insulin: \<20 µU/mL.

No interventions assigned to this group

Metabolically Abnormal Lean

i) BMI ≥18.5 but \<25.0 kg/m2; ii) maximum body circumference \<165 cm to ensure subjects fit into the PET/CT and MR scanners; iii) iii) fasting blood glucose: ≥100 mg/dl or blood glucose 2 h after an OGTT: ≥140 or fasting insulin: \>20 µU/mL.

No interventions assigned to this group

Interventions

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Weight Loss

Diet-induced weight loss (obese only)

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

All subjects

* Age: greater than or equal to 18 years but \<65 years
* Weight stable (i.e., ±2 kg for at least 3 months)
* Sedentary (less than 1 hour of structured exercise per week)
* No evidence of significant organ system dysfunction or disease (e.g., diabetes, impaired kidney function, cancer, etc.)

Metabolically Normal Lean

* BMI greater than or equal to 18.5 but \<25.0 kg/m2
* Fasting blood glucose: \<100 mg/dl
* Blood glucose 2 h after an OGTT: \<140 mg/dl
* HbA1c \<5.7 %.

Metabolically Normal Obese, likely insulin sensitive

* BMI greater than or equal to 30.0 but \<45.0 kg/m2
* Fasting blood glucose: \<100 mg/dl
* Fasting insulin: \<20 mU/l
* Blood glucose 2 h after an OGTT: \<140 mg/dl
* HbA1c \<5.7 %.

Metabolically Abnormal Obese, likely insulin resistant

* BMI greater than or equal to 30.0 but \<45.0 kg/m2
* Fasting blood glucose ≥100 mg/dl or blood glucose 2 h after an OGTT ≥140 mg/dl or fasting insulin \>20 µU/mL or HbA1c \>5.7 %.

Metabolically Abnormal Lean

* BMI greater than or equal to 18.5 but \<25.0 kg/m2
* Fasting blood glucose ≥100 mg/dl or blood glucose 2 h after an OGTT ≥140 mg/dl or fasting insulin \>20 µU/mL or HbA1c \>5.7 %.

Minimum Eligible Age

18 Years

Maximum Eligible Age

64 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes