Back to resultsVitamin D, Glucose Control and Insulin Sensitivity in African-Americans
Primary Purpose
Type 2 Diabetes
Status
Completed
Phase
Phase 2
Locations
United States
Study Type
Interventional
Intervention
cholecalciferol
microcrystalline cellulose
Sponsored by
About this trial
This is an interventional prevention trial for Type 2 Diabetes focused on measuring diabetes, vitamin D, African Americans, overweight, insulin sensitivity, glucose control
Eligibility 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
Sites / Locations
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University
Arms of the Study
Arm 1
Arm 2
Arm Type
Experimental
Placebo Comparator
Arm Label
1 vitamin D3
2
Arm Description
vitamin D3, 4000 IU/d
placebo
Outcomes
Primary Outcome Measures
Insulin secretion rate
Insulin sensitivity index
2-hr post load glucose
Secondary Outcome Measures
Full Information
1. Study Identification
Unique Protocol Identification Number
NCT00784511
Brief Title
Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
Official Title
Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
Study Type
Interventional
2. Study Status
Record Verification Date
November 2014
Overall Recruitment Status
Completed
Study Start Date
July 2008 (undefined)
Primary Completion Date
February 2011 (Actual)
Study Completion Date
February 2011 (Actual)
3. Sponsor/Collaborators
Responsible Party, by Official Title
Principal Investigator
Name of the Sponsor
Tufts University
4. Oversight
Data Monitoring Committee
No
5. Study Description
Brief Summary
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.
6. Conditions and Keywords
Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
Type 2 Diabetes
Keywords
diabetes, vitamin D, African Americans, overweight, insulin sensitivity, glucose control
7. Study Design
Primary Purpose
Prevention
Study Phase
Phase 2
Interventional Study Model
Parallel Assignment
Masking
ParticipantCare ProviderInvestigatorOutcomes Assessor
Allocation
Randomized
Enrollment
100 (Actual)
8. Arms, Groups, and Interventions
Arm Title
1 vitamin D3
Arm Type
Experimental
Arm Description
vitamin D3, 4000 IU/d
Arm Title
2
Arm Type
Placebo Comparator
Arm Description
placebo
Intervention Type
Dietary Supplement
Intervention Name(s)
cholecalciferol
Other Intervention Name(s)
vitamin D3, vitamin D
Intervention Description
4000 IU/d
Intervention Type
Other
Intervention Name(s)
microcrystalline cellulose
Other Intervention Name(s)
placebo
Intervention Description
1/d
Primary Outcome Measure Information:
Title
Insulin secretion rate
Time Frame
12 weeks
Title
Insulin sensitivity index
Time Frame
12 weeks
Title
2-hr post load glucose
Time Frame
12 weeks
10. Eligibility
Sex
All
Minimum Age & Unit of Time
40 Years
Accepts Healthy Volunteers
Accepts Healthy Volunteers
Eligibility 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
Facility Information:
Facility Name
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University
City
Boston
State/Province
Massachusetts
ZIP/Postal Code
02111
Country
United States
12. IPD Sharing Statement
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Vitamin D, Glucose Control and Insulin Sensitivity in African-Americans
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