Lack of Association Between 25(OH)D Levels and Incident Type 2 Diabetes in Older Women

  1. Nelson Watts, MD11
  1. 1Department of Epidemiology, University of Iowa, Iowa City, Iowa
  2. 2Department of Epidemiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
  3. 3Department of Statistics, Fred Hutchinson Cancer Center, Seattle, Washington
  4. 4Department of Epidemiology, University of California, Los Angeles, Los Angeles, California
  5. 5Medstar Health Research Institute and Department of Medicine, Georgetown University, Washington, District of Columbia
  6. 6Department of Medicine, Emory University, Atlanta, Georgia
  7. 7Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, Alabama
  8. 8Division of Preventive Medicine, University of California, San Diego, La Jolla, California
  9. 9Department of Geriatric Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
  10. 10Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, Tennessee
  11. 11Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
  1. Corresponding author: Jennifer G. Robinson, jennifer-g-robinson{at}uiowa.edu.

Abstract

OBJECTIVE To examine whether lower serum levels of serum 25-hydroxyvitamin (OH) D [25(OH)D] are associated with increased risk of developing type 2 diabetes.

RESEARCH DESIGN AND METHODS A post hoc analysis of three nested case-control studies of fractures, colon cancer, and breast cancer that measured serum 25(OH)D levels in women participating in the Women’s Health Initiative (WHI) Clinical Trials and Observational Study who were free of prevalent diabetes at baseline. Diabetes was defined as self-report of physician diagnosis or receiving insulin or oral hypoglycemic medication. We used inverse probability weighting to make the study population representative of the WHI population as a whole. Weighted logistic regression models compared 25(OH)D levels (divided into quartiles, clinical cut points [<50, 50–<75, ≥75 nmol/L], or as a continuous variable) using the distribution of control subjects and adjusted for multiple confounding factors.

RESULTS Of 5,140 women (mean age 66 years) followed for an average of 7.3 years, 317 (6.2%) developed diabetes. Regardless of the cut points used or as a continuous variable, 25(OH)D levels were not associated with diabetes incidence in either age or fully adjusted models. Nor was any relationship found between 25(OH)D and incident diabetes when evaluated by strata of BMI, race/ethnicity, or randomization status in the Calcium Vitamin D trial.

CONCLUSIONS Lower serum 25(OH)D levels were not associated with increased risk of developing type 2 diabetes in this racially and ethnically diverse population of postmenopausal women.

Footnotes

  • Received August 24, 2010.
  • Accepted November 27, 2010.

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  1. Diabetes Care vol. 34 no. 3 628-634
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