GSTM1 and metabolic syndrome: Among Europeans, much lower ORs were obtained despite a larger sample size and higher prevalence rates of MetS across Hb deciles: 1.89 (1.80–1.98, p < 0.0001) at Hb ≥16.24 g/dL in men and 2.35 (2.24–2.47, p < 0.0001) at Hb ≥ 14.68 g/dL in women.