Magnesium supplementation affects metabolic status and pregnancy outcomes in gestational diabetes: a randomized, double-blind, placebo-controlled trial.

BACKGROUND To our knowledge, prior research has not examined the effects of magnesium supplementation on metabolic status and pregnancy outcomes in maternal-child dyads affected by gestational diabetes (GDM). OBJECTIVE This study was designed to assess the effects of magnesium supplementation on metabolic status and pregnancy outcomes in magnesium-deficient pregnant women with GDM. DESIGN A randomized, double-blind, placebo-controlled clinical trial was performed in 70 women with GDM. Patients were randomly assigned to receive either 250 mg magnesium oxide (n = 35) or a placebo (n = 35) for 6 wk. Fasting blood samples were taken at baseline and after a 6-wk intervention. RESULTS The change in serum magnesium concentration was greater in women consuming magnesium than in the placebo group (+0.06 ± 0.3 vs. -0.1 ± 0.3 mg/dL, P = 0.02). However, after controlling for baseline magnesium concentrations, the changes in serum magnesium concentrations were not significantly different between the groups. Changes in fasting plasma glucose (-9.7 ± 10.1 vs. +1.8 ± 8.1 mg/dL, P < 0.001), serum insulin concentration (-2.1 ± 6.5 vs. +5.7 ± 10.7 μIU/mL, P = 0.001), homeostasis model of assessment-estimated insulin resistance (-0.5 ± 1.3 vs. +1.4 ± 2.3, P < 0.001), homeostasis model of assessment-estimated β-cell function (-4.0 ± 28.7 vs. +22.0 ± 43.8, P = 0.006), and the quantitative insulin sensitivity check index (+0.004 ± 0.021 vs. -0.012 ± 0.015, P = 0.005) in supplemented women were significantly different from those in women in the placebo group. Changes in serum triglycerides (+2.1 ± 63.0 vs. +38.9 ± 37.5 mg/dL, P = 0.005), high sensitivity C-reactive protein (-432.8 ± 2521.0 vs. +783.2 ± 2470.1 ng/mL, P = 0.03), and plasma malondialdehyde concentrations (-0.5 ± 1.6 vs. +0.3 ± 1.2 μmol/L, P = 0.01) were significantly different between the supplemented women and placebo group. Magnesium supplementation resulted in a lower incidence of newborn hyperbilirubinemia (8.8% vs. 29.4%, P = 0.03) and newborn hospitalization (5.9% vs. 26.5%, P = 0.02). CONCLUSION Magnesium supplementation among women with GDM had beneficial effects on metabolic status and pregnancy outcomes. This trial was registered at www.irct.ir as IRCT201503055623N39.