Regional Fat Depots and Insulin Resistance

This study is ongoing, but not recruiting participants.
Sponsor:
Collaborators:
University of California
Information provided by (Responsible Party):
Tracey McLaughlin, Stanford University
ClinicalTrials.gov Identifier:
NCT01336777
First received: March 30, 2011
Last updated: December 2, 2013
Last verified: December 2013
  Purpose

The biological basis for insulin resistance associated with obesity is unknown. By studying equally-overweight/obese individuals who are either insulin resistant or insulin sensitive, the investigators will compare characteristics of fat tissue to test several hypotheses: 1) impaired differentiation and fat storage in the subcutaneous fat depot characterize insulin resistant individuals, who have, as a result, fat in other tissues like liver and muscle, as well as more fat circulating in the blood; 2) inflammation is greater in visceral and/or subcutaneous adipose tissue depots in insulin resistant individuals as compared with insulin sensitive individuals.


Condition
Obesity
Insulin Resistance
Diabetes Mellitus Type 2

Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Cross-Sectional
Official Title: Heterogeneity of Fat Depots

Resource links provided by NLM:


Further study details as provided by Stanford University:

Primary Outcome Measures:
  • Adipose Cell Size [ Time Frame: 3 years ] [ Designated as safety issue: No ]
    Harvest adipose tissue from human biopsy. Prepare for cell size analysis using Beckman Multisizer Coulter Counter


Secondary Outcome Measures:
  • Macrophage density [ Time Frame: 3 years ] [ Designated as safety issue: No ]
    Human adipose tissue will be formalin-fixed and paraffin-blocked for immunohistochemical analysis to identify macrophage number and pattern

  • Gene Expression [ Time Frame: 3 years ] [ Designated as safety issue: No ]
    Adipose tissue from humans will be frozen and RNA prepared for measurement of relative expression of genes related to adipose cell differentiation, fat storage, and inflammation


Biospecimen Retention:   Samples With DNA

adipose tissue samples will be frozen for gene expression analysis.


Estimated Enrollment: 50
Study Start Date: August 2009
Estimated Study Completion Date: August 2014
Estimated Primary Completion Date: August 2014 (Final data collection date for primary outcome measure)
Groups/Cohorts
Insulin resistant group
there is no intervention
Insulin sensitive group
There is no intervention

Detailed Description:

Insulin resistance (IR) is a major contributor to obesity-related morbidities such as diabetes and cardiovascular disease. While obesity is associated with IR, the biological basis for this association is unclear, and not all obese individuals are IR. The once-popular portal hypothesis, which states that lipolysis from VAT in particular accounts for IR, has been questioned because VAT contributes only 15% of the total systemic free fatty acid (FFA) flux. Other proposed mechanisms linking obesity to IR include inflammation, adiponectin, and ectopic fat. It is unclear whether VAT mass is more closely linked to IR than is subcutaneous adipose tissue (SAT) mass. Furthermore, evidence linking differential biological activity to IR in VAT or SAT is indirect, largely derived from studies comparing lean to obese or VAT to SAT without evaluation of IR. Thus, the purpose of this study is to investigate the biological mechanisms by which SAT and/or VAT contribute to IR. Specifically, the investigators will explore two related hypotheses- that impaired adipocyte differentiation in SAT is related to IR, ectopic fat deposition and expansion of VAT depot, and that inflammation in VAT is associated with IR. Utilizing adipose cell size/distribution obtained by Beckman Coulter Multisizer, gene expression via quantitative PCR, in-vivo quantification of IR via a modified insulin suppression test, and CT scans of abdomen/thigh, our specific aims are to:

  1. Confirm that impairment of adipocyte differentiation in SAT is associated with IR by comparing cell size characteristics and differentiation markers in IR and IS subjects undergoing elective surgery;
  2. Test the hypothesis that the same relationship will not be seen in VAT;
  3. Demonstrate that VAT mass is expanded in the presence of impaired differentiation of adipocytes in SAT;
  4. Demonstrate that intramuscular fat is related to both IR and impaired differentiation of adipocytes in SAT using cell size characteristics and differentiation markers;
  5. Demonstrate that increased inflammation in omental fat is associated with IR independent of obesity using inflammation markers (gene and protein).
  Eligibility

Ages Eligible for Study:   39 Years to 65 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population

Healthy, nondiabetic volunteers will be recruited from Stanford's General Surgery Preoperative Clinic, Stanford's Bariatric Surgery Clinic, and nonsurgical volunteers who respond to local newspaper advertisements.

Criteria

Inclusion Criteria:

  • No major organ disease
  • Fasting blood glucose < 126 mg/dL
  • BMI 25-35 kg/m2
  • Nonpregnant/nonlactating

Exclusion Criteria:

  • pregnancy/lactation
  • major organ disease
  • drugs that influence insulin resistance
  • unstable body weight or active weight loss program
  • outside BMI range or age range
  • diabetic by fasting glucose criteria 126 mg/dL or higher
  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: NCT01336777

Locations
United States, California
Stanford University
Stanford, California, United States, 94305
Sponsors and Collaborators
Stanford University
University of California
  More Information

No publications provided by Stanford University

Additional publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Tracey McLaughlin, Associate Professor, Stanford University
ClinicalTrials.gov Identifier: NCT01336777     History of Changes
Other Study ID Numbers: 1R01 DK080436
Study First Received: March 30, 2011
Last Updated: December 2, 2013
Health Authority: United States: Institutional Review Board

Keywords provided by Stanford University:
obesity
adipocyte differentiation
inflammation
insulin resistance
visceral fat
regional fat depots

Additional relevant MeSH terms:
Diabetes Mellitus
Diabetes Mellitus, Type 2
Insulin Resistance
Obesity
Glucose Metabolism Disorders
Metabolic Diseases
Endocrine System Diseases
Hyperinsulinism
Overnutrition
Nutrition Disorders
Overweight
Body Weight
Signs and Symptoms
Insulin
Hypoglycemic Agents
Physiological Effects of Drugs
Pharmacologic Actions

ClinicalTrials.gov processed this record on August 21, 2014