First-trimester sex hormone binding globulin and subsequent gestational diabetes mellitus

OBJECTIVE: We sought to examine the association between early pregnancy levels of sex hormone binding globulin and subsequent gestational diabetes mellitus, an association that has not been studied previously. STUDY DESIGN: We conducted a nested case-control study of 44 patients with gestational diabetes mellitus and 94 women with negative third-trimester screening for gestational diabetes mellitus. Sex hormone binding globulin levels were measured from serum samples that had been collected in the first trimester, and clinical data were ascertained from prospectively collected electronic medical records. RESULTS: Compared with women without gestational diabetes mellitus, first-trimester sex hormone binding globulin levels were lower among women in whom gestational diabetes mellitus subsequently developed (187 +/- 82 nmol/L vs 233 +/- 92 nmol/L, P < .01). In logistic regression analysis that was adjusted for body mass index, age, race, smoking, blood pressure, serum testosterone and estradiol levels, and gestational age at serum collection, sex hormone binding globulin levels remained independently associated with subsequent gestational diabetes mellitus. For every 50-nmol/L increase in sex hormone binding globulin, the odds of gestational diabetes mellitus fell by 31% (odds ratio, 0.69; 95% CI: 0.48, 0.99). CONCLUSION: Sex hormone binding globulin offers a potential early marker to target women who are at risk for gestational diabetes mellitus.