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Vitamin D Associations With Renal, Bone, and Cardiovascular Phenotypes: African American-Diabetes Heart Study
Barry I Freedman1, Jasmin Divers1, Gregory B Russell1
1Department of Internal Medicine, Section on Nephrology (B.I.F.), Center for Genomics and Personalized Medicine Research (B.I.F., J.D., G.B.R., N.D.P., J.X., D.W.B.), Center for Diabetes Research (B.I.F. J.D., G.B.R., N.D.P., L.E.W., J.X.), Center for Public Health Genomics (B.I.F. J.D., G.B.R., N.D.P., D.W.B.), Division of Public Health Sciences-Department of Biostatistical Sciences (J.D., G.B.R., L.E.W.), Department of Biochemistry (N.D.P., S.C.S., J.X.), and Department of Pathology (T.C.R.), Wake Forest School of Medicine, Winston-Salem, NC 27157; and Department of Radiology (J.J.C.), Vanderbilt University School of Medicine, Nashville, TN 37240.
Context:
Vitamin D binding protein (DBP) is an important determinant of bioavailable vitamin D (BAVD) and may provide clues to racial variation in osteoporosis and atherosclerosis.
Objective:
The objective was to assess relationships between DBP, BAVD, 25-hydroxyvitamin D (25OHD), and 1,25 di-hydroxyvitamin D (1,25OH2D) with kidney, bone, adipose, and atherosclerosis phenotypes in African Americans with type 2 diabetes.
Design:
Cross-sectional (N = 545) and longitudinal (N = 288; mean 5.1 ± 0.9-year follow-up) relationships between vitamin D concentrations with renal phenotypes, vertebral bone mineral density, aorto-iliac, coronary artery, and carotid artery calcified plaque (CP), and adipose tissue volumes were studied.
Setting:
African American-Diabetes Heart Study.
Patients:
Participants were 56.7% female with mean ± standard deviation (sd) age 55.6 ± 9.6 years, diabetes duration 10.3 ± 8.2 years, and eGFR 90.9 ± 22.1 ml/min/1.73 m(2).
Interventions:
None.
Main Outcomes And Measures:
Associations tested between vitamin D and the previously mentioned phenotypes adjusting for age, sex, African ancestry proportion, diabetes duration, statins, smoking, changes in estimated glomerular filtration rate, body mass index, hemoglobin A1c, and blood pressure.
Results:
1,25OH2D was inversely associated with change in coronary artery CP (parameter estimate [β] -0.005, standard error [SE] 0.002; P = .037), with a trend for change in carotid artery CP (β -0.007, SE 0.004; P = .074). Further adjustment for renin-aldosterone-system blockade revealed inverse association between 1,25OH2D and change in albuminuria (β -0.004, SE 0.002; P = .037). DBP, BAVD, and 25OHD did not associate significantly with changes in albuminuria, CP, or bone mineral density. BAVD was inversely associated with visceral, subcutaneous, intermuscular, and pericardial adipose volumes.
Conclusions:
In contrast to BAVD and 25OHD, only 1,25OH2D levels were significantly and inversely associated with changes in subclinical atherosclerosis and albuminuria in African Americans, suggesting potential beneficial effects.