Impaired Adipogenesis in Insulin Resistance: Pilot Clinical and In Vitro Studies

This study has been completed.
Sponsor:
Collaborator:
Information provided by:
University of Vermont
ClinicalTrials.gov Identifier:
NCT00560469
First received: November 16, 2007
Last updated: February 1, 2011
Last verified: September 2010
  Purpose

Obesity is a strong risk factor for developing type 2 diabetes (T2DM), but the reasons for this are not fully understood. In particular, it is not known why some obese people develop T2DM while other obese individuals do not. This study tests whether differences in fat cells (adipocytes) are to blame. Even in adults, fat cells are constantly being formed to replace old fat cells and to respond to the body's need to store excess energy. The ability to form new fat cells may be diminished in some individuals, leading to larger fat cells. These large fat cells secrete hormones that may increase risk for T2DM. This study tests whether fat cells from obese insulin resistant subjects (who are at risk for developing T2DM) form at a slower rate than those from insulin sensitive subjects (who are at lower risk for developing T2DM).

To address this question we will recruit and study two groups of obese subjects, selected to be similar in age, gender and degree of obesity. One group of subjects will be obese and insulin resistant (the OIR group), while the other will be comparably obese, but insulin sensitive (OIS). Subjects will undergo a series of studies to characterize their metabolism including measurement of body fat by DEXA scanning, oral glucose tolerance (a test used to diagnose diabetes) and measurement of insulin sensitivity in response to an infusion of insulin (a research study used to classify patients into the OIR and OIS groups). Small samples of fat (from just under the skin of the belly and the buttocks) will obtained using a needle on two occasions over 12 weeks. During these 12 weeks, subjects will drink a small amount of water that contains a non-radioactive label. This labeled water will allow us to measure the rate of growth of new fat cells in the body. We will also look at the rate of growth of fat cells obtained from these biopsies in the laboratory.

The results of this study may tell us more about why certain obese people develop diabetes and why others do not. This might lead to new ways to prevent or treat T2DM.


Condition Intervention
Adipocyte Differentiation
Insulin Resistance
Other: Administration of 70% deuterated water

Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Cross-Sectional
Official Title: Impaired Adipogenesis in Insulin Resistance: Pilot Clinical and In Vitro Studies

Resource links provided by NLM:


Further study details as provided by University of Vermont:

Primary Outcome Measures:
  • In vitro rates of adipocyte turnover [ Time Frame: 8 weeks ] [ Designated as safety issue: No ]

Biospecimen Retention:   Samples With DNA

Adipose tissue, plasma


Enrollment: 20
Study Start Date: January 2008
Study Completion Date: July 2010
Primary Completion Date: July 2010 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
1
Men and Women over age 40 who are obese (BMI>30) and insulin-resistant.
Other: Administration of 70% deuterated water
Subjects will drink 70% deuterated water daily for 8 weeks.
2
Men and women over age 40 who are obese (BMI>30) and insulin-sensitive.
Other: Administration of 70% deuterated water
Subjects will drink 70% deuterated water daily for 8 weeks.

Detailed Description:

Overview of design: To address the specific aims of this study we will recruit and study two groups of obese subjects, selected to be similar in age, gender and BMI. Based on the results of an oral glucose tolerance test (OGTT) and hyperinsulinemic-glucose clamp, one group will be obese and insulin resistant (OIR) and one will be obese and insulin sensitive (OIS). Subjects will undergo measurement of body fat and fat distribution, oral glucose tolerance, in vivo insulin sensitivity, percutaneous needle biopsies of subcutaneous abdominal and gluteal fat and in vivo measurement of SVC and adipocyte turnover using the D2O DNA labeling technique. Adipocyte size and the expression of pro-inflammatory cytokines and adipokines will be compared in the two groups. Primary cultures of preadipocytes will be derived from subjects and proliferation and differentiation measured in vitro and compared to in vivo measures.

Measurement of adipocyte proliferation and differentiation in vivo: The stable isotope technique of Hellerstein et al. for the measurement of slowly dividing cells is based on the incorporation of deuterium oxide (D2O) into DNA. This method has been used to estimate rates of turnover of adipocytes and stromal vascular cells in healthy normal volunteers. It has not, to date, been employed to compare groups of subjects who may differ in their adipogenic propensity. A major objective of the study, therefore, is to evaluate the utility of this approach for quantifying in vivo differences in adipocyte and SVC turnover between groups that vary by insulin sensitivity and to compare the in vivo measures obtained using this technique with in vitro measures of adipogenesis.

  Eligibility

Ages Eligible for Study:   40 Years to 65 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population

Community sample

Criteria

Inclusion Criteria:

  • Men and women age 40-65 who are obese (BMI>30)and weight stable for 6 months prior to enrollment.

Exclusion Criteria:

  • Acute or chronic medical conditions that would contraindicate participation in the research testing
  • Pregnant or nursing women
  • HbA1c>6.5%
  • Active alcohol or drug abuse
  • Weight >300 pounds.
  • Smoking
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00560469

Locations
United States, Vermont
Fletcher Allen Health Care
South Burlington, Vermont, United States, 05403
Sponsors and Collaborators
University of Vermont
Investigators
Principal Investigator: Richard E Pratley, MD University of Vermont
  More Information

No publications provided

Responsible Party: Richard Pratley, MD, University of Vermont
ClinicalTrials.gov Identifier: NCT00560469     History of Changes
Other Study ID Numbers: R21 DK80386, R21DK080386, 1R21DK80386-1, 958
Study First Received: November 16, 2007
Last Updated: February 1, 2011
Health Authority: United States: Institutional Review Board
United States: Federal Government

Keywords provided by University of Vermont:
Adipokines
Inflammation
Metabolic syndrome

Additional relevant MeSH terms:
Insulin Resistance
Glucose Metabolism Disorders
Hyperinsulinism
Metabolic Diseases
Insulin
Hypoglycemic Agents
Pharmacologic Actions
Physiological Effects of Drugs

ClinicalTrials.gov processed this record on October 29, 2014