Clinical trial NCT01141192: The Effect of Vitamin D Supplementation on Glucose Metabolism in Non-Diabetic African American Adults
Official title: The Effect of Vitamin D Supplementation on Glucose Metabolism in Non-Diabetic African American Adults
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Type 2 Diabetes
Keywords: vitamin D status
25-OH D
ionized calcium
fasting glucose
hemoglobin A1c
fasting insulin
glucose metabolism
HOMA index
blood lipids
type 2 diabetes
PTH
adiposity
body fat percentage
dual energy x-ray absorptiometry
pulse wave velocity
arterial stiffness
flow-mediated dilation
African American
inflammatory markers
Lead sponsor: Augusta University
Sponsor class: OTHER
First posted: 2010-06-10
Enrollment: 48
Sex: ALL
Minimum age (years): 19
Maximum age (years): 60
Standard ages: ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: PREVENTION

Brief summary: Type 2 diabetes is more common among African Americans than Caucasians. African Americans are also at a higher risk for lower levels of vitamin D compared to other ethnic groups. The investigators don't yet know if there is a connection between not having enough vitamin D and type 2 diabetes in African Americans. Researchers have found that the less vitamin D Caucasians had the higher the chance they would have type 2 diabetes but it is less clear if this is the case for African Americans. The investigators want to better understand how vitamin D status and diabetes risk are linked in African Americans. Also, the investigators want to see if supplementation with vitamin D will improve your blood pressure, blood sugar, \& insulin. All of these are in some way related to diabetes. The investigators want to measure changes in blood sugar \& blood pressure in people who do not have diabetes with the hope of learning new information to help treat those that do have diabetes.

The investigators hypothesize that vitamin D status is related to diabetes risk measured by hemoglobin A1c (a test of glucose level over time), fasting glucose and insulin in non-diabetic African American adults and that body weight status may affect vitamin D status in response to vitamin D supplements compared to placebo.

Detailed description: Participants will be randomly assigned to receive either a 60,000 IU vitamin D3 supplement every four weeks or an inactive placebo. All investigators and the participants will be blinded to the assignment group of each participant until all testing is completed.

Eligibility criteria: Inclusion Criteria:

* African American by self-report
* In good health

Exclusion Criteria:

* Diagnosis of diabetes
* Health problems/medication affecting calcium and/or vitamin D metabolism
* Current use of vitamin/mineral/herbal/nutritional supplements
* Inability to swallow pills
* Pregnancy

Primary outcomes:
measure: Fasting glucose level before, mid-way through, and after the vitamin D3 supplement or placebo trial.
timeFrame: 16 weeks
Secondary outcomes:
measure: Serum 25-OH D levels in response to vitamin D3 supplement or placebo across a range of adiposity
timeFrame: 16 weeks
Other outcomes:
Locations:
city: Augusta
country: United States
facility: Medical College of Georgia
state: Georgia
Study officials:
affiliation: Augusta University
name: Yanbin Dong, MD, PhD
role: STUDY_DIRECTOR
References:
citation: Liu E, Meigs JB, Pittas AG, McKeown NM, Economos CD, Booth SL, Jacques PF. Plasma 25-hydroxyvitamin d is associated with markers of the insulin resistant phenotype in nondiabetic adults. J Nutr. 2009 Feb;139(2):329-34. doi: 10.3945/jn.108.093831. Epub 2008 Dec 23.
citation: Pittas AG, Dawson-Hughes B. Vitamin D and diabetes. J Steroid Biochem Mol Biol. 2010 Jul;121(1-2):425-9. doi: 10.1016/j.jsbmb.2010.03.042. Epub 2010 Mar 18.
citation: Voidonikola PT, Stamatelopoulos KS, Alevizaki M, Kollias GE, Zakopoulos NA, Lekakis JP, Anastasiou E, Theodorakis MJ, Pittas AG, Papamichael CM. The association between glycemia and endothelial function in nondiabetic individuals: the importance of body weight. Obesity (Silver Spring). 2008 Dec;16(12):2658-62. doi: 10.1038/oby.2008.431. Epub 2008 Oct 9.
citation: Liu E, Meigs JB, Pittas AG, Economos CD, McKeown NM, Booth SL, Jacques PF. Predicted 25-hydroxyvitamin D score and incident type 2 diabetes in the Framingham Offspring Study. Am J Clin Nutr. 2010 Jun;91(6):1627-33. doi: 10.3945/ajcn.2009.28441. Epub 2010 Apr 14.
citation: Zhu H, Guo D, Li K, Pedersen-White J, Stallmann-Jorgensen IS, Huang Y, Parikh S, Liu K, Dong Y. Increased telomerase activity and vitamin D supplementation in overweight African Americans. Int J Obes (Lond). 2012 Jun;36(6):805-9. doi: 10.1038/ijo.2011.197. Epub 2011 Oct 11.