Correlation between vitamin D3 deficiency and insulin resistance in pregnancy

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.