HbA1c more than 5.9 percent can ID diabetes in early pregnancy

(HealthDay)—An HbA1c threshold of ≥5.9 percent can identify all women with gestational diabetes in early pregnancy, according to a study published online Sept. 4 in Diabetes Care.

Ruth C.E. Hughes, M.B.B.Ch., from the University of Otago in New Zealand, and colleagues analyzed data from a group of women who completed an early oral glucose tolerance test (OGTT) and HbA1c tests. Pregnancy outcome data were also assessed.

In 16,122 women, HbA1c was measured at a median of 47 days' gestation. Twenty-three percent of those offered (974 women) took an early OGTT, and in this subset all 15 cases of diabetes were identified with HbA1c ≥5.9 percent. For gestational diabetes mellitus before 20 weeks this threshold was 98.4 percent specific (positive predictive value, 52.9 percent). Excluding the women referred for gestational diabetes, women with HbA1c of 5.9 to 6.4 percent had poorer pregnancy outcomes than those with HbA1c <5.9 percent (8,174 women): relative risk of major congenital anomaly was 2.67; pre-eclampsia, 2.42; shoulder dystocia, 2.47; and perinatal death, 3.96.

"HbA1c measurements were readily performed in contrast to the low uptake of early OGTTs," the authors write.