A recent study published in the International Journal of Diabetes in Developing Countries highlighted the relationship between iron levels and gestational diabetes mellitus (GDM). 
Associations of increased levels of serum ferritin and lower incidence of anemia in pregnant women with GDM were analyzed in the study. The study aimed to determine the relationship between haemoglobin, total iron binding capacity, liver iron, serum ferritin, transferrin saturation, and serum iron with GDM. 
Genetic variants were selected from GWAS summary data of the European population for the exposure variables from the blood cell consortium for haemoglobin, UK and Denmark for serum iron markers, GWAS summary data of pre-menopausal women of Iceland, and GWAS summary data of European ancestry participants of UK-Biobank. Al for MRI-derived liver iron levels. Using GWAS summary data from the FinnGen cohort, Wald’s ratios for the selected genetic variants were calculated as ratios between gestational diabetes mellitus and the variants. As the main analysis of Mendelian Randomization (MR), inverse-variance weighted means (IVWM) of Wald’s ratios were used. 
Absence of causal effects of haemoglobin (IVWM = 0.96 (0.8 – 1.14), p =0.6), total iron binding capacity (IVWM = 1.01 (0.94 – 1.08), liver iron (IVWM = 0.97 (0.87 – 1.08), p =0.6), serum iron (IVWM = 0.99 (0.87 – 1.12) and ferritin (IVWM = 0.96 (0.81 – 1.14), p =0.7)  was found in MR analysis and sensitivity analysis with gestational diabetes mellitus.