GSTM1 and gestational diabetes: After adjusting for age and pre-BMI, compared with the GG genotype, GC/CC genotype carriers have lower GDM risk in the SBP (> 110.2 mmHg) subgroup (adjusted OR=0.45, 95% CI= 0.26-0.79, P = .005), in the FPG (≤ 4.77 mmol/L) subgroup (adjusted OR=0.46, 95% CI= 0.26-0.84, P = .021), and in the Hb (≤ 5.15 mg/dl) subgroup (adjusted OR=0.50, 95% CI = 0.25-0.99, P = .049).