- ICH GCP
- US Clinical Trials Registry
- Clinical Trial NCT00001870
Study of the Effects of Vitamin C on Patients With Type 2 Diabetes
An Exploratory Study of the Effects of Oral Vitamin C Administration on Insulin Sensitivity and Vascular Reactivity in Subjects With Type 2 Diabetes
Diabetes is a disease characterized by decreased sensitivity to the action on insulin to promote sugar (glucose) use and blood vessel relaxation (vasodilation) in muscle. Insulin's ability to cause blood vessel relaxation is controlled, in part, by nitric oxide (NO).
Nitric oxide is a substance produced by the cells lining blood vessel walls (endothelium). Increased blood flow to the muscle accounts for increased sugar (glucose) to areas of the body. Therefore, if the cells of blood vessel walls (endothelium) are not functioning properly it may contribute to insulin resistance.
Injections of Vitamin C directly into the arteries have been shown to improve blood vessel reaction to nitric oxide in diabetic patients. Researchers believe this may be due to Vitamin C's ability to increase the levels of nitric oxide in blood vessels.
The goal of this study is to determine the effects of vitamin C on both insulin sensitivity and endothelium function of patients with type 2 diabetes. An additional goal of the study is to determine the effects of vitamin C on patients with vitamin C deficiency.
Patients participating in this study will undergo a series of testes to determine insulin sensitivity and blood vessel reactivity. Patients will be divided into two groups. One group will receive doses of oral vitamin C. The other group will receive doses of a placebo (inactive pill not containing vitamin C). Patients will receive the medications for four weeks and then be tested again for insulin sensitivity and blood vessel reactivity.
Researchers believe that doses of vitamin C in diabetics or patients with vitamin C deficiency will improve insulin sensitivity and function of endothelium. Results gathered form this study may provide information about vitamin C levels in diabetics and may lead to the development of new therapies to treat insulin resistance and endothelium dysfunction.
Study Overview
Status
Intervention / Treatment
Detailed Description
Study Type
Enrollment
Phase
- Phase 2
Contacts and Locations
Study Locations
-
-
Maryland
-
Bethesda, Maryland, United States, 20892
- National Center for Complementary and Alternative Medicine (NCCAM)
-
-
Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Child
- Adult
- Older Adult
Accepts Healthy Volunteers
Genders Eligible for Study
Description
INCLUSION CRITERIA:
DIABETIC SUBJECTS:
Males and non-pregnant females between the ages of 18 and 65 in good general health except for type 2 diabetes controlled with diet and/or oral hypoglycemic agents.
Patients found to have plasma vitamin C levels less than 40 microliter M, will be enrolled into the protocol and taken off hypoglycemic agents approximately one week prior to each study.
VITAMIN C-DEFICIENT CLINICAL RESEARCH VOLUNTEERS:
Adults between the ages of 18 and 35 in good general health and on no drugs or medications.
EXCLUSION CRITERIA:
ALL SUBJECTS:
Pregnancy, liver disease, pulmonary disease, renal insufficiency, coronary heart disease, heart failure, peripheral vascular disease, coagulopathy, disease predisposing to vasculitis or Raynaud's phenomenon, bleeding disorders, kidney stones, glucose-6-phosphate dehydrogenase deficiency, family history of hemochromatosis/iron overload, platelet count less than 150,000/ml blood, prothrombin time/partial thromboplastin time (PT/PTT) greater than 1 second above the normal range, inability to give informed consent for all procedures, and positive tests for HIV, or hepatitis B or C.
DIABETIC SUBJECTS:
In addition, to the above exclusion criteria, the presence of proteinuria greater than 500 mg/24 hrs, proliferative retinipathy, or diabetic neuropathy
VITAMIN C-DEFICIENT CLINICAL RESEARCH VOLUNTEERS:
All the above exclusion criteria.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Treatment
Collaborators and Investigators
Publications and helpful links
General Publications
- Martin BC, Warram JH, Krolewski AS, Bergman RN, Soeldner JS, Kahn CR. Role of glucose and insulin resistance in development of type 2 diabetes mellitus: results of a 25-year follow-up study. Lancet. 1992 Oct 17;340(8825):925-9. doi: 10.1016/0140-6736(92)92814-v.
- DeFronzo RA. Lilly lecture 1987. The triumvirate: beta-cell, muscle, liver. A collusion responsible for NIDDM. Diabetes. 1988 Jun;37(6):667-87. doi: 10.2337/diab.37.6.667. No abstract available.
- Lillioja S, Mott DM, Howard BV, Bennett PH, Yki-Jarvinen H, Freymond D, Nyomba BL, Zurlo F, Swinburn B, Bogardus C. Impaired glucose tolerance as a disorder of insulin action. Longitudinal and cross-sectional studies in Pima Indians. N Engl J Med. 1988 May 12;318(19):1217-25. doi: 10.1056/NEJM198805123181901.
Study record dates
Study Major Dates
Study Start
Study Completion
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Estimate)
Study Record Updates
Last Update Posted (Estimate)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- 990033
- 99-AT-0033
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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