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Keywords:

  • GDM;
  • GCT;
  • insulin sensitivity;
  • insulin resistance;
  • Vitamin D;
  • HOMA

Abstract

Background

The serum level of 25-hydroxyvitamin D deficiency has long been suspected as a risk factor for glucose intolerance and perhaps 1,25-dihydroxyvitamin D has a role in the regulation of insulin secretion. This study investigates the relation between 25-hydroxyvitamin D concentrations and insulin resistance in pregnant women.

Methods

A cross-sectional study was conducted on 741 pregnant women referred to five educating hospital clinics. Universal screening was performed with a GCT-50 g, and those with plasma glucose levels ≥ 7.2 mmol/L were diagnosed as GDM if they had an impaired GTT-100 g based on Carpenter and Coustan criteria. The levels of insulin and C-peptide were measured during OGTT-100 g test. The homeostasis model assessment index (HOMA) equation was used as the insulin resistance index. The concentrations of 25-hydroxyvitamin D, and PTH were also measured.

Results

Total prevalence of vitamin D deficiency (<25 nmol/L) was found in 70.6% of pregnant women. Prevalence of severe vitamin D deficiency (<12.5) in GDM patients was higher than in normoglycaemic pregnancies. The regression model revealed a strong correlation between the HOMA index and serum levels of vitamin D.

Conclusions

These results show that a positive correlation of 25(OH) vitamin D concentrations with insulin sensitivity and vitamin D deficiency could be a confirmative sign of insulin resistance. Copyright © 2007 John Wiley & Sons, Ltd.