Influence of Endothelial Function on Central and Peripheral Causes Of Exercise Impairment in Type 2 Diabetes (InsITE)

This study has been completed.
American Diabetes Association
Information provided by (Responsible Party):
University of Colorado, Denver Identifier:
First received: November 4, 2008
Last updated: December 1, 2014
Last verified: December 2014

This study will evaluate the effects of impaired blood flow regulation on exercise. It will also determine whether the effects are more important in the heart or in the skeletal muscle tissue during exercise. In addition, this study will decide whether temporarily reversing these problems will improve blood flow control, improve heart and muscle tissue function and help improve exercise capacity in person with type 2 diabetes. This study will do so using two methods: (1) by giving vitamin C through an IV and (2) a three month exercise training program. Up to 100 subjects will be enrolled in this study.

Condition Intervention
Type 2 Diabetes
Behavioral: Exercise program
Drug: Ascorbic Acid (Vitamin C)

Study Type: Interventional
Study Design: Endpoint Classification: Efficacy Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Health Services Research
Official Title: Influence Of Endothelial Function On Central and Peripheral Causes Of Exercise Impairment In Type 2 Diabetes

Resource links provided by NLM:

Further study details as provided by University of Colorado, Denver:

Primary Outcome Measures:
  • Characterize the purported cardiac dysfunction during exercise in people with type 2 diabetes mellitus (T2DM),evaluate potential changes in cardiac function following 2 interventions: Three months exercise training and acute vitamin C administration. [ Time Frame: 3 years ] [ Designated as safety issue: No ]

Enrollment: 98
Study Start Date: May 2008
Study Completion Date: October 2011
Primary Completion Date: October 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Ascorbic acid
All study subjects have ascorbic acid infusion during one exercise visit as well as a three month exercise training intervention.
Behavioral: Exercise program
Three month exercise program located at the Anschutz Medical Campus at I-225 and Colfax. The program runs three times per week for about an hour each session. Gym is open Monday - Saturday during specific hours (morning, noon, evening).
Other Name: Exercise Training
Drug: Ascorbic Acid (Vitamin C)
During one exercise study visit, 0.06 g Vit C per kg fat-free mass per 100 ml of normal saline administered; Subjects will receive a bolus of 100mL Vit C solution given at 5ml/min over 20minutes followed by a "drip-infusion" given at 1.7ml/min.
Other Names:
  • Ascorbic Acid
  • Vitamin C

Detailed Description:

The investigators have found that persons with type 2 diabetes have an impaired ability to perform exercise even without clinically apparent complications. The reasons for this marked abnormality are unknown but are important as the decreased ability to exercise could contribute to the decreased expenditure of physical activity frequently observed in this population and may potentially constitute an early marker of cardiovascular disease.

The investigators wish to evaluate the effects of impaired blood flow regulation on exercise capacity and whether the effects are more important in the heart or in the skeletal muscle tissue during exercise. In addition, the investigators are determining whether correcting these abnormalities by two methods of improving blood flow regulation (acutely infusing Vitamin C or three months of chronic exercise training) leads to improved blood flow regulation, improved heart and skeletal muscle tissue function and hence to better exercise capacity in person with type 2 diabetes. This information will provide a more mechanistic understanding of causes of abnormal exercise responses observed in person with type 2 diabetes as well as whether and to what degree responses are modifiable. Interventions that reverse the exercise defect may facilitate patient adherence to prescribed physical activity programs and potentially decrease cardiovascular mortality in this large segment of the population.


Ages Eligible for Study:   30 Years to 55 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Men and women with uncomplicated Type 2 Diabetes
  • Healthy men and women without Type 2 Diabetes
  • Patients with Type 2 Diabetes may be taking metformin or sulfonylurea drugs to treat diabetes
  • Persons with history of hypercholesteremia if controlled with statins and/or diet
  • Patients who are moderately overweight (BMI 25-37.5)
  • Must be sedentary (defined as regular exercise < 2 times a week at a low to moderate level).
  • Patients with Hemoglobin A1c (HBA1C) <8%
  • Patients between the ages of 30 to 55 years
  • Premenopausal women.
  • Former smokers who have quit smoking for at least one year
  • Absence of comorbid conditions
  • Mild neuropathy is O.K. as long as it will not hamper exercise performance.
  • Resting systolic blood pressure (SBP) < 140, Resting diastolic blood pressure (DBP) < 90
  • Total Cholesterol < 205 Triglycerides < 250 low density lipoprotein (LDL) < 130
  • Control subjects with a normal A1C and fasting glucose

Exclusion Criteria:

  • People with T2DM taking oral medications, other than metformin or sulfonylurea drugs to control their diabetes.
  • Persons treated with insulin will be excluded
  • People who are currently smoking or have not quit for at least one year
  • Controls who have immediate family history of T2DM
  • Peri-menopausal or post-menopausal women.
  • Peripheral neuropathy
  • Total cholesterol > 205
  • Regional wall motion abnormalities
  • LV wall thickness ≥1.1 cm
  • Decreased contractility (fractional shortening <30%)
  • Ischemic heart disease (abnormal resting or exercise ECG)
  • Presence of angina that would limit exercise performance
  • Pulmonary problems that would limit exercise performance
  • Systolic blood pressure >140 mmHg at rest or >250 mmHg with exercise or diastolic pressure >90 mmHg at rest or >105 mmHg with exercise
  • Persons with autonomic insufficiency, assessed by measuring variation in RR intervals with cycled breathing and by presence of a >20 mm fall in upright blood pressure without a change in heart rate
  • Proteinuria (urine protein >200 mg/dl) or a creatinine > 2 mg/dl
  • Renal disease
  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 identifier: NCT00786019

United States, Colorado
University of Colorado Denver
Aurora, Colorado, United States, 80045
Sponsors and Collaborators
University of Colorado, Denver
American Diabetes Association
Principal Investigator: Judith G Regensteiner, PhD University of Colorado, Denver
  More Information

No publications provided

Responsible Party: University of Colorado, Denver Identifier: NCT00786019     History of Changes
Other Study ID Numbers: 07-1152, UL1TR000154
Study First Received: November 4, 2008
Last Updated: December 1, 2014
Health Authority: United States: Institutional Review Board

Keywords provided by University of Colorado, Denver:
Blood vessel function

Additional relevant MeSH terms:
Diabetes Mellitus, Type 2
Diabetes Mellitus
Endocrine System Diseases
Glucose Metabolism Disorders
Metabolic Diseases
Ascorbic Acid
Growth Substances
Molecular Mechanisms of Pharmacological Action
Pharmacologic Actions
Physiological Effects of Drugs
Protective Agents processed this record on August 26, 2015