Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans

The recruitment status of this study is unknown because the information has not been verified recently.
Verified October 2010 by Tufts University.
Recruitment status was  Active, not recruiting
Sponsor:
Information provided by:
Tufts University
ClinicalTrials.gov Identifier:
NCT00784511
First received: November 3, 2008
Last updated: October 22, 2010
Last verified: October 2010
  Purpose

North American blacks tend to have low blood levels of vitamin D because pigmentation blocks vitamin D production in the skin. They also have higher rates of developing type 2 diabetes and higher rates of complications from the disease compared with whites. Although there is compelling evidence that adequate vitamin D may reduce the risk for type 2 diabetes in whites, recent evidence from a national survey demonstrated an association of vitamin D with diabetes in whites but not in blacks. However, the central hypothesis of this study is that providing enough supplemental vitamin D to blacks (raising their blood levels higher than that of most participants in the survey) will improve blood measures related to diabetes risk. The proposed study is a 12-week randomized, double-blind, placebo-controlled experiment designed to examine the effect of vitamin D supplementation (100 μg/d ) on insulin secretion, insulin sensitivity and glucose control in pre-diabetic black men and women aged 40 and older.


Condition Intervention Phase
Type 2 Diabetes
Dietary Supplement: cholecalciferol
Other: microcrystalline cellulose
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans

Resource links provided by NLM:


Further study details as provided by Tufts University:

Primary Outcome Measures:
  • Insulin secretion rate [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
  • Insulin sensitivity index [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
  • 2-hr post load glucose [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]

Estimated Enrollment: 96
Study Start Date: July 2008
Estimated Study Completion Date: February 2011
Estimated Primary Completion Date: February 2011 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1 vitamin D3
vitamin D3, 4000 IU/d
Dietary Supplement: cholecalciferol
4000 IU/d
Other Names:
  • vitamin D3
  • vitamin D
Placebo Comparator: 2
placebo
Other: microcrystalline cellulose
1/d
Other Name: placebo

  Eligibility

Ages Eligible for Study:   40 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • African-American by self designation
  • Glucose intolerance defined as FPG ≥ 100 mg/dl or A1c ≥ 5.8%
  • BMI 25.0-39.9
  • Age 40 or older

Exclusion Criteria:

Medical Conditions

  • Diabetes potentially requiring pharmacotherapy, defined as A1c > 7%
  • Uncontrolled thyroid disease
  • Current parathyroid, liver or kidney disease
  • Renal stone within 5 years
  • Sarcoidosis, current pancreatitis, active tuberculosis, hemiplegia, gout
  • Inflammatory bowel disease, colostomy, malabsorption
  • Cancer other than basal cell skin cancer within 5 years
  • Uncontrolled arrhythmia in past year
  • Albinism or other condition associated with reduced skin pigmentation
  • Pregnancy over the last 1 year
  • Intent to become pregnant
  • Menopause onset within 1 year
  • Any other unstable medical condition Laboratory Tests
  • Fasting plasma glucose < 100
  • Hemoglobin A1c > 7%
  • Laboratory evidence of liver disease (e.g. AST > 70 U/L or ALT > 72 IU/L)
  • Laboratory evidence of kidney disease (e.g. estimated glomerular filtration rate < 60 ml/min/1.73 m2).
  • Elevated spot urine calcium to creatinine ratio > 0.38 mg/dl*
  • Abnormal serum calcium (serum calcium > 10.5 mg/dl)
  • Anemia (Hematocrit < 36% in men, <33% in women) Medications (use in past three months)
  • Estrogen or testosterone
  • Prescription vitamin D
  • Lithium
  • Oral corticosteroids
  • Anti-seizure medications
  • Unstable doses of psychotropics or phenothiazines
  • Cholestyramine Supplements (current use - may discontinue after screening)
  • Vitamin D supplements, cod liver oil, calcium supplements Other
  • Body mass index less <25 or > 39.9
  • Consumption of more than 14 alcoholic drinks per week
  • Inability to attend all three study visits as scheduled
  • Inability to provide written informed consent
  • age < 40 years
  • not African-American (by self-designation)
  • Participation in another research intervention study

    • corresponds to a 24-hour urinary calcium excretion > 400 mg
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT00784511

Locations
United States, Massachusetts
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University
Boston, Massachusetts, United States, 02111
Sponsors and Collaborators
Tufts University
  More Information

No publications provided

Responsible Party: Susan Harris/Scientist I, Tufts University
ClinicalTrials.gov Identifier: NCT00784511     History of Changes
Other Study ID Numbers: 8095, ADA 7-08-CR-27
Study First Received: November 3, 2008
Last Updated: October 22, 2010
Health Authority: United States: Institutional Review Board

Keywords provided by Tufts University:
diabetes
vitamin D
African Americans
overweight
insulin sensitivity
glucose control

Additional relevant MeSH terms:
Diabetes Mellitus
Diabetes Mellitus, Type 2
Insulin Resistance
Glucose Metabolism Disorders
Metabolic Diseases
Endocrine System Diseases
Hyperinsulinism
Cholecalciferol
Vitamin D
Ergocalciferols
Vitamins
Insulin
Micronutrients
Growth Substances
Physiological Effects of Drugs
Pharmacologic Actions
Bone Density Conservation Agents
Hypoglycemic Agents

ClinicalTrials.gov processed this record on April 17, 2014