Correction of Vitamin D Levels and Its Effect on Insulin Resistance and Weight Gain in Obese Youth
Condition: Obesity; Insulin Resistance; Vitamin D Deficiency
MeSH terms: Insulin Resistance; Vitamin D Deficiency
Intervention: Vitamin D3
Intervention description: Vitamin D3, liquid formulation, 5000 IU/mL.
Intervention MeSH terms: Vitamin D; Cholecalciferol
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Enrollment: 109.0
Sex: All
Minimum age: 6 Years
Maximum age: 17 Years
Healthy volunteers: No
Keywords: Obesity; Insulin Resistance; Vitamin D Deficiency; Children; Adolescents

Summary:

      Vitamin D deficiency is extremely common in obese youth. In our obese population followed in
      the Endocrinology clinic at Children's Medical Center Dallas, vitamin D levels were inversely
      correlated with a measure of insulin resistance. We propose to show that correction of
      vitamin D levels in obese children and adolescents improves their insulin sensitivity. Obese
      youth presenting to the Center for Obesity and its Consequences on Health (COACH) clinic will
      be randomized to receive either the most recent Institute of Medicine (IOM) recommendations
      of minimum D3 dose of 600 IU/day (1), or receive higher doses of D3 such that the blood
      levels of vitamin D will be brought to a target level in either the low part or high part of
      the normal range. The goal is to determine if correction of vitamin D deficiency will improve
      insulin sensitivity in this group. Secondary goals include determining whether correction of
      vitamin D deficiency in obese adolescents and children results in less weight gain, and
      determining the amount of D3 required to correct vitamin D levels in this population.

      Our specific hypotheses are as follows:

      Hypothesis #1 Obese youth treated with Vitamin D3 who achieve low-normal 25-hydroxyvitamin D3
      (OHD) levels (30-50 ng/mL) or high-normal 25-OHD levels (60-80 ng/mL) will have improved
      insulin resistance, as measured by Homeostatic Model Assessment of Insulin Resistance
      (HOMA-IR), compared to those individuals with deficient 25-OHD levels (< 30 ng/mL).

      Hypothesis #2 Subjects with a higher BMI will have higher Vitamin D dose requirements than
      current IOM recommendations of 600 IU/day and will take a longer period of time to reach
      target 25-OHD levels.

      Hypothesis #3 Subjects with normal 25-OHD levels will demonstrate less weight gain compared
      to subjects on the control arm.
    

Eligibility criteria:

        Inclusion Criteria:

          -  age 6-17 years

          -  BMI > 95% for age

          -  serum 25-OH D level < or + to 25 ng/mL

        Exclusion Criteria:

          -  BMI < 95% for age

          -  serum 25-OH D level > 25 ng/mL

          -  current Vitamin D supplementation > 400 IU/day

          -  anti-convulsant therapy, anti-hypertensive therapy, lipid lowering medication

          -  any medications that affect glucose metabolism (e.g., metformin, insulin)

          -  daily glucocorticoid therapy

          -  diabetes

          -  any disorders of bone or calcium metabolism

          -  hepatic or renal disease

          -  any malabsorptive disorder

          -  baseline serum Calcium > 11 ng/dL (> 2 SD above the mean)

          -  any genetic disorder that predisposes to obesity (e.g., Prader Willi

          -  hypothalamic obesity