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Effect of Vitamin D Supplementation on Oral Glucose Tolerance Among Obese Adolescents

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01856946
Recruitment Status : Completed
First Posted : May 20, 2013
Last Update Posted : October 10, 2016
Information provided by (Responsible Party):
Aneesh Tosh, University of Missouri-Columbia

Brief Summary:

Childhood obesity is a rapidly growing epidemic in the US and the world. Current estimates suggest that 30% of our nation's children are either overweight ot obese. Obesity is a major risk factor towards the development of insulin resistance, which, in turn is a major risk factor for the development of type 2 diabetes. Prior research has suggested that vitamin D therapy may be a safe, inexpensive, and effective method of reducing insulin resistance and a person's risk of developing diabetes.

The investigators' prior studies have shown that daily 4,000 IU vitamin D therapy is a safe and effective method of improving insulin resistance based on a calculation called the HOMA-IR.

The next step in identifying whether vitamin D truly improves insulin resistance is to use oral glucose tolerance testing (OGTT), which is a better real-life measure of insulin resistance compared to the previously used HOMA-IR.

Condition or disease Intervention/treatment Phase
Insulin Resistance Dietary Supplement: 4,000 IU vitamin D3 Not Applicable

Detailed Description:

The investigators intend to recruit 20 obese adolescent subjects from the PI's obesity clinic to participate in the study. Investigators expect 5 to drop out, therefore leaving 15 subjects to complete the study. Eligible and assenting subjects (with consent from a parent) will be admitting to the Pediatric Procedure Suite and MU Women's and Children's Hospital. They will have an IV placed in the arm by a nurse experienced with working with children. The subjects will have blood drawn from the IV checking for vitamin D level, insulin, glucose, and c-peptide level (another marker for insulin status). The subject will then be asked to drink a 75 gram glucose solution. Additional blood will be drawn from the IV site to check for glucose, insulin, and c-peptide levels at 30 minutes, 60 minutes, 90 minutes, and 120 minutes. A total of 30 mL (2 tablespoons) of blood will be drawn that day. The subject will have the IV removed and will be discharged to then take two 2,000 IU vitamin D3 pills (total 4,000 IU) daily for six months.

At a routine 3 months clinical visit, the subject will be tested for routine, standard of care, basic metabolic profile (BMP) with 4 ml of blood (less than 1 teaspoon) to assess for high calcium levels, a potential complication of vitamin D therapy. In the investigators' previous study of adolescents taking 4,000 IU vitamin D daily for six months, no subject developed a high calcium level.

At six months, the subject will return to the Pediatric procedure suite to have another OGTT and labs via IV as described above.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 15 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Effect of 4,000 IU Vitamin D3 Supplementation on Oral Glucose Tolerance Among Vitamin D Deficient Obese Adolescent
Study Start Date : May 2013
Actual Primary Completion Date : February 2014
Actual Study Completion Date : February 2014

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Vitamin D

Arm Intervention/treatment
Experimental: 4,000 IU Vitamin D3
two 2,000 IU vitamin D3 pills (total 4,000 IU) daily for six months.
Dietary Supplement: 4,000 IU vitamin D3
two 2,000 IU vitamin D3 pills (total 4,000 IU) daily for six months.

Primary Outcome Measures :
  1. change in oral glucose tolerance [ Time Frame: baseline and 6 months ]
    Will obtain oral glucose tolerance tests at baseline and at 6 months to determine change

Information from the National Library of Medicine

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Ages Eligible for Study:   9 Years to 19 Years   (Child, Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Obese adolescent (BMI >85th percentile for age)
  • 9-19 years of age
  • attending the ADOBE clinic at the University of Missouri
  • 25OH vitamin D level within past 3 months

Exclusion Criteria:

  • use of vit D supplements other than standard multi-vitamin preparation (i.e., should not be receiving vit D > 1000 IU/d)
  • use of medications that interfere with vit D metabolism (e.g., anti-convulsive)
  • history of hepatic or renal disorders, hypercalciuria, or hypercalcemia
  • undergoing UV radiation as medical therapy
  • pregnancy; cigarette smoking; current use of a tanning bed
  • current type 2 diabetes
  • any current antihyperglycemic medication use (e.g. metformin, insulin) less than one month prior to initial OGTT.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01856946

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United States, Missouri
University of Missouri Adolescent Obesity Clinic
Columbia, Missouri, United States, 65201
Sponsors and Collaborators
University of Missouri-Columbia
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Principal Investigator: Aneesh K Tosh, MD. MS University of Missouri-Columbia
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Responsible Party: Aneesh Tosh, Associate Professor, University of Missouri-Columbia Identifier: NCT01856946    
Other Study ID Numbers: 1203853
First Posted: May 20, 2013    Key Record Dates
Last Update Posted: October 10, 2016
Last Verified: October 2016
Additional relevant MeSH terms:
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Insulin Resistance
Glucose Metabolism Disorders
Metabolic Diseases
Vitamin D
Growth Substances
Physiological Effects of Drugs
Bone Density Conservation Agents
Calcium-Regulating Hormones and Agents