GSTM1 and gestational diabetes: When the women were analysed separately according to GDM status, no correlations were seen between Hb and fasting glucose (GDM: r = −0.05, p = 0.56 and non-GDM: r = −0.11, p = 0.11) or between ferritin levels and fasting glucose (GDM; r = 0.04, p = 0.68 and non-GDM; r = 0.12, p = 0.13).