Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
Completed · Phase 2 · Has a placebo group
Conditions studied: Type 2 Diabetes
In brief
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.
Key facts
- Study ID
- NCT00784511
- Run by
- Tufts University
- People needed
- 100
- Starts
- 2008-07-01
- Expected to finish
- 2011-02-01
- Last updated by the study team
- 2014-11-14
Who can join
Age: 40 and older. Sex: any. Healthy volunteers: accepted.
You may qualify if…
- 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
You may not qualify if…
- 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
Where it is running
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University — Boston, Massachusetts, United States
Full record on ClinicalTrials.gov
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