Vitamin D and Glucose Metabolism in Pediatrics

Study Overview
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Brief Summary
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The discovery that the vitamin D receptor is expressed in more than 30 tissues indicates that the physiologic functions of vitamin D are much broader than its well-known role in the regulation of calcium absorption and bone metabolism. There is evidence that vitamin D is involved in the pathogenesis of cancer, cardiovascular disease, multiple sclerosis, and type I diabetes. Recent epidemiological evidence points to a strong association between vitamin D insufficiency and insulin resistance, the metabolic syndrome, and type II diabetes. The investigators would like to examine the role of vitamin D in the development of insulin resistance in overweight children and adolescents, which represent a high risk population for cardiovascular and metabolic complications. The investigators propose a prospective randomized clinical trial of vitamin D supplementation in overweight, insulin resistant, vitamin D deficient children. The investigators objective is to assess if changes in insulin resistance, fasting lipid profiles, blood pressure, and inflammatory markers occur in these patients post treatment with vitamin D. Additionally, concomitant changes in calcium and bone metabolism after vitamin D treatment will be evaluated. This is because, contrary to adults, the optimal vitamin D concentrations that regulate calcium and bone metabolism have not been established in pediatrics.

Official Title
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Vitamin D Concentrations and Their Effect on Glucose Metabolism in Pediatrics

Conditions
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Insulin Resistance, Obesity, Vitamin D25 Insufficiency

Intervention / Treatment
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* Drug: Vitamin D drops
* Drug: Placebo drops


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI>85th% for age & sex Vitamin D25 between 10-20ng/ml Normal serum Ca concentrations >8.5mg/dl Evidence of insulin resistance (measured by HOMA-IR, and QUICKI indices) Exclusion Criteria: Vitamin D25<10ng/ml No parental consent No evidence of insulin resistance BMI < 85th percentile Known diagnosis of type 1 or 2 diabetes Severe underlying disease such as liver disease, end-stage renal disease, or malignancy Present medication that affects insulin sensitivity such as steroids or Metformin Any chronic illness or administration of medications that is associated with fat malabsorption as they may interfere with vitamin D absorption. Known history of hypocalcemia, calcium disorder (such as Di George syndrome) Serum Calcium concentration < 8.5mg/dl Other drugs that might effect vitamin D metabolism due to induction of P450 enzyme activity.

Ages Eligible for Study
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Minimum Age: 7 Years
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Vitamin D<br>Subjects will randomly be assigned to Vitamin D drops versus placebo drops. | Drug: Vitamin D drops<br>* Subjects will be randomly assigned to Vitamin D 3,000 Units per day or Placebo drops.<br>|
| Placebo Comparator: Placebo<br>Subjects will randomly be assigned to Vitamin D drops versus placebo drops. | Drug: Placebo drops<br>* Subjects will be randomly assigned to Vitamin D 3,000 Units per day or Placebo drops.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To determine changes in insulin sensitivity induced by vitamin D supplementation in obese children with insulin resistance. | To our knowledge, there are no prospective randomized clinical trials on examining the effects of vitamin D treatment on insulin resistance and bone metabolism in vitamin D deficient, insulin resistant, obese children. We would like to determine if giving Vitamin D supplementation to obese children will help reduce their insulin resistance. We plan to measure Vitamin D levels and HOMA-IR at baseline and compare this to levels post-supplementation. Our timeframe is baseline and 4 months. | 4 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To quantify the associations between vitamin D 25 concentration, insulin resistance, and calcium metabolism in overweight children. | The normal values for vitamin D are not standardized. In children, it is generally accepted, that vitamin D25 levels>20ng/ml are indicative of vitamin D sufficiency. Data in adults, however, suggest that this cutoff for vitamin D sufficiency should be raised to greater than 30ng/ml. Analysis of bone metabolism in this study will give some insight to the effects of vitamin D treatment in this population of children, and may help further define acceptable vitamin D levels in determining vitamin D deficiency and insufficiency. Our timeframe is baseline and 4 months. | 4 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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insulin resistance, obesity, adolescence, vitamin D supplementation