The Association Between Vitamin D Deficiency and Diabetes in Adult African Americans and Whites: An NHANES Study.

Objective: The primary objective of this cross-sectional study is to investigate the association between vitamin D deficiency (VDD) and diabetes and see if this association is the same for adult (age ≥ 20) African Americans (AAs) and Whites. The secondary objective is to examine the distribution of the 25-hydroxyvitamin D test among AAs and Whites and to evaluate the appropriateness of using the same cut-off point for both groups to diagnose VDD.

Methods: Our analysis is based on the 2011-2014 National Health and Nutrition Examination Surveys (NHANES). We used two common propensity score adjustment methods to analyze the data-propensity score matching (PSM) and the inverse probability of treatment weighting (IPTW).

Results: The prevalence of diabetes for AAs and Whites was 12.27% (95% CI, 10.47-14.07%) and 7.24% (95% CI, 6.35-8.13%), respectively. The prevalence of VDD for AAs and Whites was 65.29% (95% CI, 62.01-68.58%) and 19.49% (95% CI, 16.53-22.45%), respectively. Under PSM, the odds ratios for the diabetes-VDD association for AAs and Whites were 0.94 (95% CI, 0.70-1.27) and 2.16 (95% CI, 1.49-3.13), respectively. Under IPTW, the VDD-diabetes odds ratios for AAs and Whites were 0.83 (95% CI, 0.64-1.10) and 2.35 (95% CI, 1.67-3.30), respectively. Our results further demonstrate that the 25-hydroxyvitamin D measurements are significantly different for AAs and Whites across the general population, as well as the vitamin D-sufficient and vitamin D-deficient populations.

Conclusion: The prevalence of VDD and diabetes was higher for AAs compared to Whites. However, VDD was associated with increased diabetes risk for Whites but not for AAs. Though more research is needed to explain why this is the case, a reason for this may be that the 25-hydroxyvitamin D test or its associated cut-off point for defining VDD may not accurately reflect the vitamin D status among AAs.