SHBG and diabetes mellitus: PCOS itself does not independently contribute to an increased risk of GDM; instead, the elevated GDM risk in PCOS is linked to other potential factors, including testosterone, high-density lipoprotein, sex hormone-binding globulin, body mass index, waist-hip ratio, apolipoprotein A-I, number of children, illnesses of parents and siblings (diabetes), hemoglobin A1c, fasting insulin, fasting blood glucose, years of schooling.