Vitamin D insufficiency and abnormal hemoglobin a1c in black and white older persons

J Gerontol A Biol Sci Med Sci. 2015 Apr;70(4):525-31. doi: 10.1093/gerona/glu122. Epub 2014 Aug 11.

Abstract

Background: Although vitamin D has been mechanistically linked to insulin secretion and sensitivity, it remains unclear whether low 25-hydroxyvitamin D levels confer an increased risk of impaired glucose metabolism. We evaluated the relationship between vitamin D insufficiency (25-hydroxyvitamin D < 20ng/mL) and abnormal hemoglobin A1c (A1c) (≥6.5%) in community-dwelling older persons and examined whether this relationship differed according to race.

Methods: Participants were 2,193 persons of age 70-79 years at Year 1 (52% women; 37% black) in the Health, Aging, and Body Composition study who had clinic visits at Years 2 and 4. Logistic regression analyses, adjusted for potential confounders, were used to evaluate the association between vitamin D insufficiency and abnormal A1c 2 years later. Interaction of race and vitamin D insufficiency was tested.

Results: A total of 665 (30%) and 301 (14%) of the participants had vitamin D insufficiency at Year 2 and abnormal A1c at Year 4, respectively. After controlling for demographics, other potential confounders, and diabetes status at Year 4 (n = 477 diabetics), we found that vitamin D insufficiency was associated with an increased likelihood of having abnormal A1c (odds ratio = 1.56; 95% CI: 1.03-2.37). We also found that this relationship persisted among the 1,765 participants without diabetes in Year 2 (odds ratio = 2.33; 95% CI: 1.00-5.40). Findings did not differ by race.

Conclusions: Vitamin D insufficiency was associated with abnormal A1c levels among black and white older persons independent of diabetes status. Future studies are needed to establish the temporal relationship between vitamin D and A1c in diverse samples of older persons.

Keywords: Hemoglobin A1c; Older persons.; Vitamin D.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • African Americans / statistics & numerical data*
  • Aged
  • Biomarkers / blood
  • Body Mass Index
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / complications
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / ethnology*
  • European Continental Ancestry Group / statistics & numerical data*
  • Female
  • Glycated Hemoglobin A / metabolism*
  • Humans
  • Independent Living
  • Longitudinal Studies
  • Male
  • Medicare / statistics & numerical data
  • Pennsylvania / epidemiology
  • Predictive Value of Tests
  • Sensitivity and Specificity
  • Tennessee / epidemiology
  • United States
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood
  • Vitamin D Deficiency / blood*
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / diagnosis
  • Vitamin D Deficiency / ethnology*

Substances

  • Biomarkers
  • Glycated Hemoglobin A
  • Vitamin D
  • 25-hydroxyvitamin D