Skeletal Muscle Lipid and Insulin Resistance: Effects of Physical Activity and Weight Loss (SHELL)

July 26, 2017 updated by: Bret Goodpaster, University of Pittsburgh

102 late- life adults at risk for developing type 2 diabetes mellitus, will be randomized to one of three interventions designed to improve insulin sensitivity thereby potentially preventing future progression of type 2 diabetes. The investigators predict that insulin sensitivity will improve equally following either weight loss or exercise, while there will be additive effects from combined intervention.

The investigators hypothesize that weight loss will decrease intermuscular adipose tissue, intramyocellular lipid, and visceral abdominal adipose tissue.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The primary objective of this project will be to examine the role of skeletal muscle lipid and capacity for fat oxidation in insulin resistance in older adults who either are at high risk for the development of type 2 diabetes mellitus (T2DM) or who are untreated newly diagnosed T2DM. A randomized intervention trial will be conducted to examine the effects of physical activity and weight loss, alone or in combination, on intramyocellular lipid (IMCL), intermuscular adipose tissue (IMAT) and abdominal AT (adipose tissue), oxidative capacity and insulin resistance.

The first aim is to examine the effects of weight loss without exercise on AT distribution, intramyocellular lipid (IMCL) and oxidative capacity of skeletal muscle in conjunction with improvements in insulin sensitivity. We will test the hypotheses that weight loss without exercise will: 1) Improve insulin sensitivity, decrease the lipid interspersed within muscle (intermuscular AT), intramyocellular lipid (IMCL), as well as visceral abdominal AT (VAT); and 2) Will have no effects on either skeletal muscle oxidative capacity determined in vitro or in vivo.

A second aim is to examine the effects of exercise without weight loss on AT, IMCL, oxidative capacity and insulin resistance. We will test the hypotheses that exercise without weight loss will: 1) Increase the oxidative enzyme capacity of muscle; 2) Increase IMCL despite having little effect on AT distribution within muscle (intermuscular AT) or visceral AT; 3) Improve insulin sensitivity to a similar degree as weight loss without exercise.

A third aim will be to examine the combined effects of exercise and weight loss on insulin resistance. Our third hypotheses are that combining weight loss and exercise will 1) Decrease IMAT, VAT and have little overall effect on IMCL 2) Improve the oxidative capacity of skeletal muscle; 3) Confer synergistic improvements in insulin sensitivity through the combined actions on AT and skeletal muscle capacity for oxidation.

A fourth aim will be to examine the combined effects of exercise and weight loss on subjects with newly diagnosed but untreated T2DM. Our final hypotheses are that exercise and weight loss will have similar effects in subjects with newly diagnosed T2DM compared to those at risk for developing T2DM with regards to improved insulin sensitivity, body composition and oxidative capacity of skeletal muscle.

Study Type

Interventional

Enrollment (Actual)

102

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Pennsylvania
      • Pittsburgh, Pennsylvania, United States, 15213
        • University of Pittsburgh

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

60 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • 60-75 years of age
  • Stable weight (No Gain/Loss of > 10 lbs in 6 months)
  • Impaired Glucose Tolerance or Newly, untreated, undiagnosed type 2 diabetes
  • Sedentary
  • Non-smoker
  • BMI 25.0-38.0 KG/M2
  • Resting Blood Pressure ≤ 150mmHg systolic and ≤ 95 mmHg diastolic
  • IGT: Fasting Glucose > 100, < 126 2-Hour OGTT > 140 but < 200
  • T2D: Fasting Glucose > 126 < 2000 2-Hour OGTT > 200
  • Note from PCP/Cardiologist for exercise clearance if positive stress test symptoms were observed from GXT

Exclusion Criteria:

  • Clinically significant CVD including h/o MI
  • Peripheral Vascular Disease
  • Hepatic, renal, muscular/neuromuscular, or active hematologic/oncologic disease
  • Clinically diminished pulse
  • Presence of bruits in lower extremities
  • Previous history of pulmonary emboli
  • Peripheral Neuropathy
  • Currently not engaged in a regular program and have a VO2 max pre-training value > 55 ml/kg-fat free mass-min., indicative of moderate fitness.
  • Anemia (Hematocrit < 34%)
  • Any contraindications to moderate exercise (Please specify)
  • Inability and/ or unwillingness to comply with the protocol as written
  • Active alcohol or substance abuse (Past 5 Years)
  • Total cholesterol > 300 mg/dL
  • Triglyceride > 350 mg/dL
  • ALT > 80, AST > 80, Alk Phos > 240
  • Proteinuria (defined as >1 + on routine dipstick), hypothyroidism (sTSH>8)
  • Therapeutic Doses of Nicotinic Acid
  • Oral glucocorticoids
  • Females currently on hormone replacement therapy (HRT) less than 6 months
  • Claustrophobia
  • Previous difficulty with lidocaine or other local anesthetic

  • Stress test symptoms:

    • Positive ECG (> 2mm ST segment depression) without PCP cardiologist permission to participate
    • Signs or symptoms of cardiovascular decomposition (hypotensive response to exercise)
    • Onset of angina or angina like symptoms, shortness of breath, change in heart rhythm, signs of poor perfusion (light-headedness), tightness,
    • Hypotension

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 1
Weight Loss
Behavioral: Weight Loss
The reduction of kcal/day through implementation of low fat diet
Experimental: 2
Exercise
Behavioral: Exercise
16 week intervention; 6 exercise sessions weekly w 3 supervised exercise sessions weekly utilizing cycling or walking/jogging. Participants maintain exercise diaries: wks 1-4; 30 minutes at 60-70% MHR, wks 5-8; 40 minutes at 60-70% MHR, weeks 9-16; 40 minutes at 75% MHR
Experimental: 3
Exercise and Weight Loss
Behavioral: Exercise and weight loss

Exercise: 16 week intervention; 6 exercise sessions weekly w 3 supervised exercise sessions weekly utilizing cycling or walking/jogging. Participants maintain exercise diaries: wks 1-4; 30 minutes at 60-70% MHR, wks 5-8; 40 minutes at 60-70% MHR, weeks 9-16; 40 minutes at 75% MHR.

Weight Loss: Reduction of kcal/day through implementation of a low fat diet.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Effects of physical activity and weight loss, alone or in combination, on intramyocellular lipid, intermuscular adipose tissue and abdominal AT, oxidative capacity and insulin resistance.
Time Frame: 16 weeks
16 weeks

Secondary Outcome Measures

Outcome Measure
Time Frame
Assess the mechanisms by which these interventions may prevent the development of diabetes
Time Frame: 16 weeks
16 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Pittsburgh

Collaborators

American Diabetes Association

Investigators

  • Principal Investigator: Bret H Goodpaster, PhD, University of Pittsburgh

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

June 1, 2004

Primary Completion (Actual)

August 1, 2011

Study Completion (Actual)

August 1, 2011

Study Registration Dates

First Submitted

October 2, 2008

First Submitted That Met QC Criteria

October 2, 2008

First Posted (Estimate)

October 3, 2008

Study Record Updates

Last Update Posted (Actual)

July 31, 2017

Last Update Submitted That Met QC Criteria

July 26, 2017

Last Verified

July 1, 2017

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 0406003

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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