Study of the Effects of Vitamin C on Patients With Type 2 Diabetes

NCT00001870 | Completed Phase 2

• 2 other identifiers: 99003399-AT-0033
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Diabetes Mellitus, Non-Insulin Dependent; Non-Insulin Dependent

Keywords

Insulin Resistance; Oxidative Stress; Antioxidant; Endothelial Function; Glucose Clamp; Type 2 Diabetes; Vitamin C Deficiency

Interventions

Acetylcholine DRUG

Eligibility Criteria

• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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:
• VITAMIN C-DEFICIENT CLINICAL RESEARCH VOLUNTEERS:

Sponsors & Collaborators

• National Center for Complementary and Integrative Health (NCCIH): lead

Study Sites (1)

National Center for Complementary and Alternative Medicine (NCCAM)

Bethesda, Maryland, 20892, United States

Location

Related Publications (3)

• 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.

  PMID: 1357346 BACKGROUND

• 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.

  PMID: 3289989 BACKGROUND

• 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.

  PMID: 3283552 BACKGROUND

MeSH Terms

Conditions

Diabetes Mellitus, Type 2; Insulin Resistance; Ascorbic Acid Deficiency

Interventions

Acetylcholine

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases; Hyperinsulinism; Avitaminosis; Deficiency Diseases; Malnutrition; Nutrition Disorders

Intervention Hierarchy (Ancestors)

Biogenic Amines; Amines; Organic Chemicals

Study Design

• Study Type: interventional
• Phase: phase 2
• Purpose: TREATMENT
• Sponsor Type: NIH

Study Record Dates

• First Submitted: November 3, 1999
• First Posted: November 4, 1999
• Study Start: January 1, 1999
• Study Completion: December 1, 2004
• Last Updated: March 4, 2008

Record last verified: 2004-12

Locations

US (1)