Influence of Oral Zinc and Magnesium Supplementations on Metabolic Status and Pregnancy Outcomes in Pregnant Women with Gestational Diabetes Mellitus: A Systematic Literature Review
Abstract Background: Incidences of Gestational Diabetes Mellitus (GDM) have significantly increased worldwide; however, no agreement on the best dietary interventions for improving blood glucose has been established. Recent studies have suggested the potential benefits of Zinc (Zn) and Magnesium (Mg) supplements in optimizing glycaemic control due to their essential role in glucose metabolism and insulin action, though results were varied. Objective: This review aims to assess the efficacy of oral Zn and Mg-supplementations on the glycaemic indices of pregnant women (PW) with GDM as a primary outcome, and further, to examine their impact on lipid biomarkers and incidence of adverse pregnancy outcomes (APOs), as secondary outcomes. Method: A literature search in the Cochrane Library (CENTRAL), Embase, MEDLINE, and PubMed, for English language articles published between 2000-2020, was undertaken. All controlled clinical trials that administered oral Zn or Mg-supplementation and investigated their impact on glycaemic indices in PW with GDM were included in this review. Seven studies fulfilled the predefined eligibility criteria. Results: Altogether, four studies and five studies, with a combined sample size of 232 and 290 women, which administered Zn and Mg, respectively, were included in this review. Based on the mean change of measured parameters that estimated by independent t-test, Zn-supplementation resulted in a significant reduction of FPG (P=0.01) and HOMA-IR (P=0.02), whereas Mg-intervention was associated with a significant reduction of FPG (P<0.001), insulin (P=0.03), and HOMA-IR (P=0.03). Further, a significant reduction of TC (P=0.04) and Triglycerides (P=0.02) were shown following Zn and Mg-supplementations, respectively. Concerning APOs, Zn-intervention was associated with favourable influence on reducing incidence of preeclampsia (5.2% vs. 8.7%) and macrosomia (3.3% vs.16.6%), while the potential benefit of Mg-intervention was limited to macrosomia (4.6% vs.15.3%). Conclusion: Administration of Zn and Mg, either alone or combined with multi-nutrients, for six weeks, is suggested as an adjunctive intervention for optimizing glycaemic control in GDM, though their notable beneficial influence on lipid biomarkers and APOs was limited and requires further investigation. Additional high-quality, and large-scale trials from various countries are warranted to validate the current findings. Keywords: Gestational Diabetes Mellitus, Zinc, Magnesium, Glycaemic Control, Lipid Profile, Adverse Pregnancy Outcomes.