The Effect of Vitamin D Repletion on Insulin Resistance

NCT00606957 | Completed

• 1 other identifier: RUH IRB# AGR-0623
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

The reason for doing this study is to learn whether raising a person's vitamin D level from below normal to normal levels will improve his or her body's ability to use sugar. Vitamin D is well known to be an important vitamin for the development and maintenance of bones. Recently, scientists have learned that vitamin D may have a role in the prevention of cancer, diabetes, and autoimmune diseases. The investigators are specifically interested in studying this question in the overweight/obese population as they are at greater risk for both vitamin D deficiency and impaired ability to metabolize sugar (glucose intolerance). Primary Hypotheses: Vitamin D repletion (increasing the serum 25(OH)D level from ≤ 20 ng/ml to ≥ 30 ng/ml) will improve insulin sensitivity in individuals who are overweight/obese and insulin resistant. Secondary Hypotheses: 1.Vitamin D repletion will improve biomarkers of cardiovascular risk and inflammation (directly altering macrophage cytokine production and/or indirectly as a result of improvement in insulin sensitivity.) 2.30,000 IU (0.25 mg) weekly of cholecalciferol (vitamin D3) will raise serum 25(OH)D levels from ≤ 20 ng/ml to ≥ 30 ng/ml overweight/obese population.

Conditions

Obesity

Keywords

Obesity; Metabolism

Outcome Measures

Primary Outcomes (1)

• The primary outcome is change in insulin sensitivity over time, as measured by the glucose clamp, HOMA and OGTT.

  14 weeks

Interventions

Vitamin D3 (cholecalciferol) DIETARY_SUPPLEMENT

Vitamin D will be taken orally, 10,000 IU (0.25 mg) three times per week.

Eligibility Criteria

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

You may qualify if:

• Nonsmoking men and women, ages 18-65
• Body mass index (BMI) ≥ 28 kg/m² and within 10% of maximum weight
• Serum 25(OH)D level ≤ 20 ng/ml
• Serum insulin level ≥ 7.2 mU/l
• Willingness to maintain current body weight for the duration of the study
• Willingness to maintain baseline lifestyle activities and routines for the duration of the study
• Willingness to avoid the use of non-steroidal anti-inflammatory drugs (NSAIDS), including low-dose daily aspirin, for at least ten days prior to each admission (due to the potential effects of these agents on inflammatory markers.)
• Willingness to avoid the use of all over-the-counter or prescription vitamins, dietary supplements, and herbal products during the study, with the exception of a basic multivitamin supplement.
• If of childbearing potential, willingness to use highly effective contraception for the duration of the study.

You may not qualify if:

• Current tobacco smoking
• History of bleeding or coagulation disorders
• Gastrointestinal disease resulting in significant gastrointestinal dysfunction or malabsorption
• History of diabetes, or diagnosed during screening OGTT
• Current treatment with hypertensive medications
• History of cardiovascular disease
• Renal disease, as evidenced by a serum creatinine above the upper limit of normal on more than one screening visit
• History of kidney stones
• History of chronic hepatitis, or liver enzymes (AST or ALT) more than 2.5 times the upper limit of normal
• Primary hyperparathyroidism or baseline hypercalcemia from any cause
• Current treatment with over-the-counter or prescription weight loss medications, such as orlistat or sibutramine
• History of bariatric surgery
• Current treatment with any cholesterol-lowering medications, such as statins, niacin, fibrates, or ezetimibe
• Blood pressure ≥ 145/90 after ten minutes of rest on more than one screen visit
• Hyperthyroidism or untreated hypothyroidism. Subjects with chronic, treated, stable hypothyroidism may be included in the study at the discretion of the Principal Investigator.

Sponsors & Collaborators

• Rockefeller University: lead

Study Sites (1)

Rockefeller University

New York, New York, 10021, United States

Location

MeSH Terms

Conditions

Obesity

Interventions

Cholecalciferol

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Cholestenes; Cholestanes; Steroids; Fused-Ring Compounds; Polycyclic Compounds; Sterols; Vitamin D; Secosteroids; Membrane Lipids; Lipids

Study Officials

• Allegra Grossman, MD

  The Rockefeller University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER

Study Record Dates

• First Submitted: January 22, 2008
• First Posted: February 5, 2008
• Study Start: January 1, 2008
• Primary Completion: May 1, 2009
• Study Completion: May 1, 2009
• Last Updated: October 13, 2011

Record last verified: 2011-10

Locations

US (1)