GSTM1 and osteoporosis: There were inverse associations of Hb level with osteoporosis in males < 65 years old, males ≥ 65 years old, and females ≥ 65 years old (aOR = 0.87, 95% CI = 0.83–0.92, p < 0.001 for <65-year-old males; aOR = 0.94, 95% CI = 0.92–0.97, p < 0.001 for ≥65-year-old males; and aOR = 0.98, 95% CI = 0.96–0.99, p = 0.011 for ≥65-year-old females).