The Relationship of Serum 25-Hydroxyvitamin D and Insulin Resistance Among Nondiabetic Canadians: A Longitudinal Analysis of Participants of a Preventive Health Program

PLoS One. 2015 Oct 21;10(10):e0141081. doi: 10.1371/journal.pone.0141081. eCollection 2015.

Abstract

Observational and intervention studies have revealed inconsistent findings with respect to the relationship between vitamin D and insulin resistance. No intervention studies have been conducted in community samples whereas this may be particularly relevant to the primary prevention of type 2 diabetes (T2D) and cardiovascular disease (CVD). In the present study we examined whether temporal improvements in vitamin D status, measured as serum 25-hydroxyvitamin D [25(OH)D], reduce the risk of insulin resistance among individuals without T2D. We accessed and analyzed data from 5730 nondiabetic participants with repeated measures of serum 25(OH)D who enrolled in a preventive health program. We used the homeostatic model assessment for insulin resistance (HOMA-IR) and applied logistic regression to quantify the independent contribution of baseline serum 25(OH)D and temporal increases in 25(OH)D on HOMA-IR. The median time between baseline and follow up was 1.1 year. On average serum 25(OH)D concentrations increased from 89 nanomoles per liter (nmol/L) at baseline to 122 nmol/L at follow up. Univariate analyses showed that relative to participants with baseline serum 25(OH)D less than 50 nmol/L, participants with baseline concentrations of "50-<75", "75-<100", "100-<125", and ≥125 nmol/L were 0.76 (95% confidence intervals: 0.61-0.95), 0.54 (0.43-0.69), 0.48 (0.36-0.64) and 0.36 (0.27-0.49) times as likely to have insulin resistance at follow up, respectively. More importantly, relative to participants without temporal increases in 25(OH)D, those with increases in serum 25(OH)D of "<25", "25-<50", "50-<75", "≥75" nmol/L were 0.92 (0.72-1.17), 0.86 (0.65-1.13), 0.66 (0.47-0.93), and 0.74 (0.55-0.99) times as likely to have insulin resistance at follow up, respectively. In the subgroup of participants without insulin resistance at baseline, this was 0.96 (0.72-1.27), 0.78 (0.56-1.10), 0.66 (0.44-0.99), and 0.67 (0.48-0.94), respectively. These observations suggest that improvements in vitamin D status reduce the risk for insulin resistance and herewith may contribute to the primary prevention of T2D and CVD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / physiology
  • Calcifediol / blood
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / physiopathology
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / physiopathology
  • Female
  • Health Promotion / methods
  • Humans
  • Insulin / blood
  • Insulin Resistance / physiology*
  • Logistic Models
  • Longitudinal Ligaments
  • Male
  • Risk Factors
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood

Substances

  • Blood Glucose
  • Insulin
  • Vitamin D
  • 25-hydroxyvitamin D
  • Calcifediol

Grant support

This is an analysis of secondary data. The data had been collected for the purpose of lifestyle counseling of participants by a preventive health program. None of the authors were involved in the execution of this program; neither did they provide financial support. P.J.V. holds a Canada Research Chair in Population Health, an Alberta Research Chair in Nutrition and Disease Prevention, and an Alberta Innovates Health Scholarship. The funding for the Canada Research Chair is provided through the Canadian Institutes for Health Research to the University of Alberta. The Alberta Research Chair is awarded by the School of Public Health at the University of Alberta through a thematic research contract with the Pure North S’Energy Foundation. The Health Scholarship is funded by the Alberta provincial government through Alberta Innovates Health Solutions. The funders had no role in analytic design, data analysis, decision to publish, or preparation of this manuscript.