Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
试验速览
- 阶段
- 2 期
- 状态
- 已完成
- 入组人数
- 100
- 试验地点
- 2
- 主要终点
- Insulin secretion rate
研究概览
简要总结
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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Prevention
- 盲法
- Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
入排标准
- 年龄范围
- 40 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •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
排除标准
- •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
- •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
结局指标
主要结局
Insulin secretion rate
时间窗: 12 weeks
Insulin sensitivity index
时间窗: 12 weeks
2-hr post load glucose
时间窗: 12 weeks
次要结局
未报告次要终点