A Prospective Study On Correlation Between First-trimester Sex Hormone Binding Globulin And Subsequent Gestational Diabetes Mellitus

Pregnancies that are complicated by gestational diabetesmellitus (GDM) are associated with increases in both maternal andneonatal morbidity. A 50-g glucose challenge test, which is thecurrent recommendation, is not conducted typically until 24 to 28weeks of gestation. Definitive testing with a 3-hour 75-g glucosetolerance test, subsequent monitoring of blood glucose levels,instruction in diet, and, if necessary, the initiation of medicationrequie further time. Such scheduling leaves only a narrow windowduring which these interventions can be applied before delivery.Earlier identification and treatment of pregnancies with, or at riskfor, GDM might offer an opportunity for improved outcomes. Innonpregnant subjects, low levels of sex hormone binding globulin(SHBG) have been associated with insulin resistance and thesubsequent development of type 2 diabetes mellitus. Amongpregnant women, low levels of SHBG have been found at the timeof the diagnosis of GDM. In this prospective study, we sought todetermine whether reduced levels of SHBG that are measured inearly pregnancy are associated with the subsequent development ofGDM. OBJECTIVE: We sought to examine the associationbetween SHBG in first trimester of pregnancy and subsequentdevelopment of GDM. STUDY DESIGN: We conducted a nestedcase-control study of 41 patients with GDM and 734 women withnegative third-trimester screening for GDM. SHBG levels weremeasured from serum samples that had been collected in the firsttrimester, and clinical data were ascertained from prospectivelycollected electronic medical records. RESULTS: Both groupsshowed no differences in Age of gestation, blood pressure, Bodymass index (BMI), Nulliparous, Gestational age at serum sampling,Testosterone (T) and Estradiol (E2). First-trimester SHBG levelswere lower among women in whom GDM subsequently developed(269.55 ± 119.35nmol/L vs 321.77 ± 124.21nmol/L, P<0.05)compared with normoglycemic control subjects. In patients withsevere GDM and insulin therapy significantly lower levels ofSHBG than in those with dietary treatment only were found(227.32 ± 118.39nmol/L vs 282.65 ± 128.47nmol/L, P<0.05).SHBG was inversely correlated to BMI and T. In logistic regressionanalysis that was asjusted for BMI, age, gestational age at serumcollection, serum T and E2 levels, SHBG levels remainedindependently associated with subsequent GDM. CONCLUSION:Sex hormone binding globulin offers a potential early marker totarget women who are at risk for gestational diabetes mellitus.