New Test May Predict Gestational Diabetes Better

Gestational diabetes is a type of diabetes that occurs during a woman's pregnancy, increasing the mother's risk of delivering a large-for-gestational-age baby, which can lead to pre-term birth, fetal injury, perinatal mortality and cesarean delivery.

Gestational diabetes is also a risk factor for preeclampsia and gestational hypertension. Since treatment of gestational diabetes can lessen the risk of adverse pregnancy outcomes, practice guidelines recommend screening all non-diabetic, pregnant women for the disease.

Scientists at Brigham and Women's Hospital conducted a case-control study of 1,000 pregnant women who were receiving standard prenatal care at the hospital. Included in the study were 500 women who had a normal glucose challenge test (control subjects) and 500 women who failed the glucose challenge test and required a subsequent oral glucose tolerance test (case patients).

The team's primary goal was to assess the accuracy of the diabetes biomarker, plasma glycated CD59 (pGCD59), in predicting the results of the standard of care glucose challenge test used to screen for gestational diabetes. They assessed whether pGCD59 could predict the following: the results of the glucose challenge test (GCT) for screening of gestational diabetes mellitus (GDM) (primary analysis); and the diagnosis of GDM and prevalence of large for gestational age (LGA) newborns (secondary analyses).

The scientists found that, when compared with the control subjects, the median plasma GCD59 value was 8.5-fold higher in the patients who failed the glucose challenge test and 10-fold higher in the subset of these patients who met diagnostic criteria for gestational diabetes in the subsequent oral glucose tolerance test. They also found that higher plasma GCD59 levels at gestational week 24-28 were associated with higher prevalence of large-for-gestational-age newborns, with the higher the level, the higher the risk (4% higher risk for patients in the lowest quartile of GCD59 plasma levels, and 14% in the highest quartile).

Out of the 58 large-for-gestational-age babies born to mothers that failed the glucose challenge test in this study, 80% were born to mothers who did not meet oral glucose tolerance test criteria for gestational diabetes, but had median plasma GCD59 levels 7-fold higher than control women with a normal glucose challenge test. These findings are consistent with other studies showing that women who fail the glucose challenge test, but do not meet criteria for gestational diabetes, are still at a higher risk of abnormal pregnancy outcomes, including delivering large for gestational age babies.

The team concluded that as non-enzymatic glycation inactivates the complement inhibitor CD59, forming glycated CD59 (GCD59), they could therefore use a sensitive and specific enzyme-linked immunosorbent assay (ELISA) for GCD59 in blood, and they showed that plasma GCD59 levels are significantly higher in individuals with type 2 diabetes and independently predict the response to the oral glucose tolerance test.

Jose A. Halperin, MD, a hematologist and senior author of the study said, “This is the first study to demonstrate that a single measurement of plasma GCD59 can be used as a simplified method to identify women who are at risk for failing the glucose challenge test and are at higher risk for developing gestational diabetes. These results suggest that a single measurement of plasma GCD59 during weeks 24-28 may also help stratify the risk for delivering larger infants among women with gestational glucose intolerance.” The study was published in the April 2017 issue of the journal Diabetes Care.