Impact of Vitamin D Replacement on Markers of Glucose Metabolism and Cardio-Metabolic Risk in Women with Former Gestational Diabetes--A Double-Blind, Randomized Controlled Trial

PLoS One. 2015 Jun 9;10(6):e0129017. doi: 10.1371/journal.pone.0129017. eCollection 2015.

Abstract

Gestational Diabetes Mellitus (GDM) and vitamin D deficiency are related to insulin resistance and impaired beta cell function, with heightened risk for future development of diabetes. We evaluated the impact of vitamin D supplementation on markers of glucose metabolism and cardio metabolic risk in Asian women with former GDM and hypovitaminosis D. In this double blind, randomized controlled trial, 26 participants were randomized to receive either daily 4000 IU vitamin D3 or placebo capsules. 75 g Oral Glucose Tolerance Test (OGTT) and biochemistry profiles were performed at baseline and 6 month visits. Mathematical models, using serial glucose, insulin and C peptide measurements from OGTT, were employed to calculate insulin sensitivity and beta cell function. Thirty three (76%) women with former GDM screened had vitamin D level of <50 nmol/L at baseline. Supplementation, when compared with placebo, resulted in increased vitamin D level (+51.1 nmol/L vs 0.2 nmol/L, p<0.001) and increased fasting insulin (+20% vs 18%, p = 0.034). The vitamin D group also demonstrated a 30% improvement in disposition index and an absolute 0.2% (2 mmol/mol) reduction in HbA1c. There was no clear change in insulin sensitivity or markers of cardio metabolic risk. This study highlighted high prevalence of vitamin D deficiency among Asian women with former GDM. Six months supplementation with 4000 IU of vitamin D3 safely restored the vitamin D level, improved basal pancreatic beta-cell function and ameliorated the metabolic state. There was no effect on markers of cardio metabolic risk. Further mechanistic studies exploring the role of vitamin D supplementation on glucose homeostasis among different ethnicities may be needed to better inform future recommendations for these women with former GDM at high risk of both hypovitaminosis D and future diabetes.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Asians
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • C-Peptide / blood
  • Diabetes, Gestational / blood*
  • Female
  • Humans
  • Insulin / blood
  • Metabolic Syndrome / blood
  • Metabolic Syndrome / etiology
  • Metabolic Syndrome / prevention & control*
  • Pregnancy
  • Vitamin D / administration & dosage
  • Vitamin D / therapeutic use*
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / drug therapy*
  • Vitamin D Deficiency / ethnology
  • Vitamins / adverse effects
  • Vitamins / therapeutic use*

Substances

  • Biomarkers
  • Blood Glucose
  • C-Peptide
  • Insulin
  • Vitamins
  • Vitamin D

Grant support

This study received funding from Penang Medical College and Medical Research Grant from Ministry of Health, Malaysia (MRG 2011 02). The vitamin D and placebo capsules were supplied without charge by Blackmore Ltd. The funders and supplier have no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.