With two piecewise regression models, the adjusted OR of developing MetS was 0.964 (95% CI, 0.959–0.969; P < 0.001) among people with SHBG < 76.653 nmol/L, but there was no correlation between SHBG and MetS in participants with SHBG ≥ 76.653 nmol/L. This evidence concerns the gene SHBG and metabolic syndrome.