Effect of Vitamin D Supplementation on the Incidence of Gestational Diabetes

Background: The aim of this study was survey of the effect of Vitamin D supplementation on the incidence of gestational diabetes (GDM) in pregnant women. Materials and Methods: This randomized clinical trial was conducted at Alzahra and Shahid Beheshti Hospital in Isfahan, Iran, from January, 2013 to January, 2014 on 210 pregnant women referred to gynecology clinics. Serum levels of Vitamin D were measured, and those with lower serum levels of 10 nmol/L randomly divided into two groups of A and B. Pregnant women with normal Vitamin D level assigned as Group C. Group A was given 50,000 IU Vitamin D supplement every 2 weeks for 10 weeks, and Group B were given the omega-3 pearl as placebo. Then, the incidence of GDM was measured in 24–26 weeks of pregnancy with glucose tolerance test and compared in three groups. Data were analyzed using SPSS version 20 by descriptive statistics, Chi-square and Logistic regression. Results: The mean age of participants was 24.76 years (8.02 standard deviation, range 16–36 years). The incidence of GDM at 24–26 weeks gestational age were 8.57% in normal Vitamin D group, 10.00% in Vitamin D deficiency with treatment group, and 11.43% in Vitamin D deficiency without treatment group. The difference between groups in terms of incidence of GDM was not statistically significant (P = 0.112). Conclusion: Vitamin D supplementation had not effect on incidence of GDM during pregnancy.