SHBG and gestational diabetes: There was a causal relationship between testosterone, high-density lipoprotein, sex hormone-binding globulin, body mass index, waist-hip ratio, apolipoprotein A-I, number of children, illnesses of mother, father and siblings: diabetes, hemoglobin A1c, fasting insulin, fasting blood glucose, years of schooling and GDM according to the IVW method.