Zinc Supplementation and the Effects on Pregnancy Outcomes in Gestational Diabetes: a Randomized, Double-blind, Placebo-controlled Trial

Objective: The current study was designed to determine the beneficial effects of zinc intake on biomarkers of inflammation, oxidative stress, and pregnancy outcomes among pregnant women with gestational diabetes (GDM). Methods: This randomized, double-blind, placebo-controlled clinical trial was conducted among 50 women with GDM. Patients were randomly allocated to intake either 233mg zinc gluconate (containing 30mg zinc) (n=25) or a placebo (n=25) for 6 weeks. Fasting blood samples were taken at the fist of the study and after 6 weeks of intervention to quantify related variables. Newborn's weight, height, head circumference, Apgar score, and hyperbilirubinemia were determined. Results: The change in serum zinc levels after 6 weeks of supplementation was greater in women consuming zinc than in the placebo group (+8.513.5 vs. -3.6 +/- 16.2mg/dL, P=0.006). Changes in serum high sensitivity C-reactive protein (hs-CRP) (-110.1 +/- 1475.5 vs. +1137.8 +/- 2429.2ng/mL, P=0.03) and plasma total antioxidant capacity (TAC) concentrations (+60.0 +/- 129.0 vs. -28.4 +/- 81.4mmol/L, P=0.006) were significantly different between the supplemented women and placebo group. We did not find any significant effect of zinc administration on pregnancy outcomes. Conclusion: Taken together, zinc administration among patients with GDM was associated with decreased hs-CRP and increased TAC concentrations; however, it did not influence maternal plasma nitric oxide (NO), glutathione (GSH), malondialdehyde (MDA) levels, or pregnancy outcomes.