Low levels of Sex-Hormone-Binding Globulin predict insulin requirement in patients with gestational diabetes mellitus

Low Sex-Hormone-Binding Globulin (SHBG) levels indicating a state of hyperandrogenicity - are associated with a higher risk for the development of non-insulin dependent diabetes (NIDDM) in women and are accepted as a marker of muscular insulin resistance. To analyze whether low SHBG values are also present in patients with gestational diabetes, we investigated levels of SHBG in 42 patients with gestational diabetes mellitus (GDM) in comparison with 48 pregnant women with normal glucose tolerance (NGT). Beside maternal parameters like body-mass index (BMI), HbA1c, fasting, 1- and 2-hour blood glucose and insulin concentrations, parameters of the new-borns (head-circumference, body weight, height and sex) were recorded. Maternal and neonatal variables were then related to SHBG levels. Both groups showed no differences in BMI, height, weight or age of gestation. Patients with GDM revealed significantly lower levels of SHBG than pregnant women with NGT(512 +/- 249 nmol/l vs. 643 +/- 137 nmol/l: p < 0.01). In patients with severe GDM and insulin therapy significantly lower levels of SHBG than in those with dietary treatment only were found (223 +/- 210 nmol/l vs. 592 +/- 102 nmol/l; p < 0.001). SHBG was inversely correlated to BMI (r = -0.30, p < 0.01), 1-hour (r= -0.20 p < 0.05) and 2-hour blood glucose levels (r = -0.30; p < 0.01). In summary, we found significantly lower levels of SHBG in patients with GDM, especially in those who developed severe GDM and required insulin therapy during the last months of pregnancy.