Association between early oxidative DNA damage and iron status in women with gestational diabetes mellitus

•Relationship between oxidative DNA damage and iron status in GDM was investigated.•LC–MS/MS was used to quantify 8−OH-dG, S-cdA and R-cdA levels.•In the first trimester, urinary 8−OH-dG levels were found higher in the GDM group.•The women with ferritin ≥50th centile demonstrated higher levels of 8−OH-dG, R-cdA.•This is the first study where DNA damage is evaluated in first and second trimesters. This study aims to assess the relationship between oxidative DNA damage and iron status in women with gestational diabetes mellitus (GDM) compared to those with normal glucose tolerance in the first and the second trimesters of pregnancy. Maternal serum and urine samples were collected in the 11th-14th weeks and the 24th-28th weeks of gestation. In addition to oral glucose tolerance test in the second trimester, fasting blood glucose, HbA1c, ferritin and hemoglobin levels were measured in blood samples. Urinary levels of oxidative DNA damage products 8-hydroxy-2′-deoxyguanosine (8−OH-dG) and 8,5′-cyclo-2′-deoxyadenosines (S-cdA, R-cdA) were determined using liquid chromatography-tandem mass spectrometry with isotope-dilution. In the first trimester, urinary 8−OH-dG levels were found higher in the GDM group (n = 33) than in the control group (n = 84) (p = 0.006). R-cdA and S-cdA levels were not significantly different between the two groups (p = 0.794 and p = 0.792 respectively). When the cases were stratified according to their first trimester ferritin levels, women with ≥50th centile (≥130 ng/mL) demonstrated higher levels of 8−OH-dG and R-cdA than those under