Vitamin D and Type 2 Diabetes Study

Not Applicable

Completed

Conditions: Type 2 Diabetes
Prediabetes

Interventions: Dietary Supplement: Vitamin D (Cholecalciferol)
Other: Placebo

Registration Number: NCT01942694

Lead Sponsor: Tufts Medical Center

Brief Summary: The goal of the Vitamin D and type 2 diabetes (D2d) study is to determine if vitamin D supplementation works to delay the onset of type 2 diabetes in people at risk for the disease and to gain a better understand how vitamin D affects glucose (sugar) metabolism.

Detailed Description: The goal of the Vitamin D and type 2 diabetes (D2d) study is to determine if vitamin D supplementation works to delay the onset of type 2 diabetes in people at risk for the disease and to gain a better understand how vitamin D affects glucose (sugar) metabolism. Researchers at US sites will enroll people with pre-diabetes (people who have higher than normal blood glucose level but not high enough to meet the diagnosis of diabetes). The study will enroll participants over approximately 2 years and participants will be followed for approximately 3 years. Participants will receive either Vitamin D or a placebo by chance. Participants will take 1 pill a day for the duration of the study.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 2423

Inclusion Criteria

Pre-diabetes ("at increased risk for diabetes") defined by meeting 2-out-of-3 of the following glycemic criteria at the baseline visit:
1. Fasting plasma glucose (FPG) 100-125 mg/dL
2. 2-hour plasma glucose (2hPG) 140-199 mg/dL
3. Hemoglobin A1c (HbA1c) 5.7-6.4%
Age ≥ 30 years .(≥25 years for people of the following races: American-Indian, Alaska Native, Native Hawaiian or Other Pacific Islander).
Body Mass Index ≥ 24.0 (22.5 for Asians) and ≤ 42.0 kg/m2
Provision of signed and dated written informed consent prior to any study procedures.

Major

Exclusion Criteria

Diabetes based on either of the following criteria:
1. History (past 1 year) of hypoglycemic pharmacotherapy (oral or injectable medication approved by the FDA for type 2 diabetes), used for any condition (e.g. pre-diabetes, diabetes, polycystic ovarian syndrome.
2. Meeting the diagnosis criteria for diabetes
History (past 3 years) of hyperparathyroidism, nephrolithiasis or hypercalcemia.
Pregnancy (past 1 year by report or positive pregnancy test at screening), intent to become pregnant in the next 4 years or unprotected intercourse. History of gestational diabetes is not an exclusion criterion.
Currently breastfeeding.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Vitamin D (Cholecalciferol)	Vitamin D (Cholecalciferol)	One vitamin D pill daily
Placebo	Placebo	One pill daily

Primary Outcome Measures

Name	Time	Method
Time to Development of Diabetes	Approximately 48 months	New-onset diabetes was based on annual glycemic testing of fasting plasma glucose, glycated hemoglobin, and 2-hour post-load plasma glucose and semiannual testing of fasting plasma glucose and glycated hemoglobin. If two or three of the glycemic measures met the 2010 ADA thresholds for diabetes, the participant was considered to have met the diabetes outcome. When only the measure for fasting plasma glucose or glycated hemoglobin met the threshold, confirmatory testing was performed for the positive measure within 8 weeks. If only the measure for 2-hour post-load plasma glucose met the threshold, then a 75-g oral glucose tolerance test to reassess all three glycemic measures was repeated. If the repeat measure was positive or both fasting plasma glucose and glycated hemoglobin were positive (in the case of a repeat oral glucose tolerance test), than the participant was considered to have met the diabetes outcome.

Secondary Outcome Measures

Name	Time	Method
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Age	Approximately 48 months
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: 25OHD Concentration	Approximately 48 months
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Race (as a Proxy for Skin Pigmentation)	Approximately 48 months	Race and ethnic group were reporting by the participant. The category "other" includes American Indian or Alaska Native; Native Hawaiian or other Pacific Islander; and other race. Ethnic group includes any race.
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Pre-diabetes Criteria (Two vs. Three Criteria)	Approximately 48 months	Participants met at least two of three glycemic criteria for prediabetes: fasting plasma glucose level, 100 to 125 mg per deciliter (5.6 to 6.9 mmol per liter); plasma glucose level 2 hours after a 75-g oral glucose load, 140 to 199 mg per deciliter (7.8 to 11.0 mmol per liter) (impaired glucose tolerance); and glycated hemoglobin level, 5.7 to 6.4% (39 to 47 mmol per mole).
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: BMI	Approximately 48 months
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Waist Circumference	Approximately 48 months
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Geographic Location (as a Proxy for Sun Exposure)	Approximately 48 months
Variability of Response to Vitamin D Supplementation by Baseline Characteristic: Calcium Intake From Supplements	Approximately 48 months
Blood Plasma 25OHD Concentration.	Approximately 48 months
Number of Participants With Adverse Events.	Approximately 48 months
Change in Blood Pressure as a Continuous Variable.	Approximately 48 months
Number of Participants Who Discontinue Study Pills.	Approximately 48 months
Change in FPG as a Continuous Variable.	Every 12 months for approximately 48 months
Change in 2hPG as a Continuous Variable.	Every 12 months for approximately 48 months.
Change in HbA1c as a Continuous Variable.	Every 6 months for approximately 48 months
Measurement of Insulin Resistance (Derived From the OGTT).	Every 12 months for approximately 48 months
Measurement of Beta Cell Secretion (Derived From the OGTT)	Every 12 months for approximately 48 months
Identification of Characteristics Associated With the Variability in Achieved 25OHD Concentration.	Every 12 months for approximately 48 months

Trial Locations

Locations (25): University of Texas Southwestern Medical Center
🇺🇸
Dallas, Texas, United States
Pennington Biomedical Research Center
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Baton Rouge, Louisiana, United States
Duke University
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Durham, North Carolina, United States
Cleveland Clinic
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Cleveland, Ohio, United States
Kaiser Permanente Center for Health Research
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Portland, Oregon, United States
Northwestern University
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Chicago, Illinois, United States
Omaha VA Medical Center
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Omaha, Nebraska, United States
University of Nebraska Medical Center
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Omaha, Nebraska, United States
Southwest American Indian Center
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Phoenix, Arizona, United States
University of Colorado, Denver
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Aurora, Colorado, United States
University of Southern California
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Los Angeles, California, United States
Stanford University
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Palo Alto, California, United States
Tulane University Health Sciences
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New Orleans, Louisiana, United States
MedStar Community Clinical Research Center
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Hyattsville, Maryland, United States
Atlanta VA Medical Center
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Decatur, Georgia, United States
Orlando VA Medical Center
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Orlando, Florida, United States
Florida Hospital Translational Research Institute
🇺🇸
Orlando, Florida, United States
Maine Medical Center
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Scarborough, Maine, United States
Tufts Medical Center
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Boston, Massachusetts, United States
Health Partners Riverside Clinic
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Minneapolis, Minnesota, United States
Beth Israel Medical Center
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New York, New York, United States
Medical University of South Carolina
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Charleston, South Carolina, United States
University of Tennessee Health Science Center
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Memphis, Tennessee, United States
Baylor College of Medicine
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Houston, Texas, United States
University of Kansas Medical Center
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Kansas City, Kansas, United States