Abstract P144: Race and Vitamin D Binding Protein Gene Polymorphisms Modify the Association between 25-Hydroxyvitamin D and Incident Diabetes: The Atherosclerosis Risk in Communities (ARIC) Study
Background: Low 25-hydroxyvitamin D [25(OH)D] levels are associated with diabetes, but few studies have examined racially diverse populations while also accounting for potential differences by race in common vitamin D binding protein (DBP) gene polymorphisms. DBP, the primary carrier protein for 25(OH)D, is associated with lower bioavailable vitamin D levels and may inhibit the action of vitamin D on target cells. We sought to evaluate whether the association between 25(OH)D and incident diabetes may vary by race and key DBP gene polymorphisms.
Methods: We studied 8,120 white and 2,102 black adults aged 46-70 years at baseline (1990-92) from the ARIC Study with follow-up for incident diabetes during study visits conducted in 1993-95 and 1996-98. Adjusted hazard ratios (HR) and their 95% CIs for diabetes were estimated according to 25(OH)D. Potential effect modification by race or DBP gene polymorphisms was tested with the inclusion of multiplicative interaction terms.
Results: During follow-up there were 750 incident cases of diabetes. The association of 25(OH)D with diabetes varied by race (p-interaction 0.004). Among whites, compared to those in the highest quintile of 25(OH)D, the adjusted HRs (95% CIs) for diabetes among those in quintiles 4 through 1 were 1.39 (1.06, 1.83), 1.06 (0.79, 1.42), 1.32 (0.99, 1.77), and 1.59 (1.17, 2.16), respectively (p-trend 0.01). No association was observed among blacks (p-trend 0.12). Presence of the rs4588 A allele, reported to be associated with high DBP levels, modified the association between 25(OH)D and diabetes among whites, but not blacks (p-interaction 0.01 and 0.38, respectively; Table).
Conclusions: Low 25(OH)D levels were associated with risk for diabetes among whites, but not blacks, with the strongest associations observed among those genetically predisposed to high DBP levels. The effects of vitamin D supplementation for the prevention of diabetes may differ by race and bioavailable vitamin D levels.
Author Disclosures: J.P. Reis: None. E.D. Michos: None. E. Selvin: None. J.S. Pankow: None. P.L. Lutsey: None.
- © 2015 by American Heart Association, Inc.