Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
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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.
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Ages Eligible for Study:
40 Years and older (Adult, Senior)
Sexes Eligible for Study:
Accepts Healthy Volunteers:
African-American by self designation
Glucose intolerance defined as FPG ≥ 100 mg/dl or A1c ≥ 5.8%
Age 40 or older
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