Effects of calcium–vitamin D co-supplementation on glycaemic control, inflammation and oxidative stress in gestational diabetes: a randomised placebo-controlled trial

This study was designed to assess the effects of calcium and vitamin D supplementation on the metabolic status of pregnant women with gestational diabetes mellitus (GDM).

This randomised placebo-controlled trial was performed at maternity clinics affiliated to Kashan University of Medical Sciences, Kashan, Iran. Participants were 56 women with GDM at 24–28 weeks’ gestation (18 to 40 years of age). Subjects were randomly assigned to receive calcium plus vitamin D supplements or placebo. All study participants were blinded to group assignment. Individuals in the calcium–vitamin D group (n = 28) received 1,000 mg calcium per day and a 50,000 U vitamin D₃ pearl twice during the study (at study baseline and on day 21 of the intervention), and those in the placebo group (n = 28) received two placebos at the mentioned times. Fasting blood samples were taken at study baseline and after 6 weeks of intervention.

The study was completed by 51 participants (calcium–vitamin D n = 25, placebo n = 26). However, as the analysis was based on an intention-to-treat approach, all 56 women with GDM (28 in each group) were included in the final analysis. After the administration of calcium plus vitamin D supplements, we observed a significant reduction in fasting plasma glucose (−0.89 ± 0.69 vs +0.26 ± 0.92 mmol/l, p < 0.001), serum insulin levels (−13.55 ± 35.25 vs +9.17 ± 38.50 pmol/l, p = 0.02) and HOMA-IR (−0.91 ± 1.18 vs +0.63 ± 2.01, p = 0.001) and a significant increase in QUICKI (+0.02 ± 0.03 vs −0.002 ± 0.02, p = 0.003) compared with placebo. In addition, a significant reduction in serum LDL-cholesterol (−0.23 ± 0.79 vs +0.26 ± 0.74 mmol/l, p = 0.02) and total cholesterol: HDL-cholesterol ratio (−0.49 ± 1.09 vs +0.18 ± 0.37, p = 0.003) and a significant elevation in HDL-cholesterol levels (+0.15 ± 0.25 vs −0.02 ± 0.24 mmol/l, p = 0.01) was seen after intervention in the calcium–vitamin D group compared with placebo. In addition, calcium plus vitamin D supplementation resulted in a significant increase in GSH (+51.14 ± 131.64 vs −47.27 ± 203.63 μmol/l, p = 0.03) and prevented a rise in MDA levels (+0.06 ± 0.66 vs +0.93 ± 2.00 μmol/l, p = 0.03) compared with placebo.

Calcium plus vitamin D supplementation in women with GDM had beneficial effects on their metabolic profile.

www.​irct.​ir IRCT201311205623N11

The study was supported by a grant (no. 92110) from Kashan University of Medical Sciences.