ADA: Gestational Diabetes Findings Show No Risk Cutoff

CHICAGO, June 27 -- Elevated glucose levels during pregnancy appear to increase risks to mother and baby even at levels below established criteria for gestational diabetes, researchers reported here.

In a large international prospective study, rising maternal glucose in the third trimester was associated with an increasing risk of cesarean delivery, fetal obesity, and high insulin and low glucose levels in infants at delivery, said Boyd E. Metzger, M.D., of Northwestern University, and colleagues.

The likelihood of problems increased linearly through even the maternal glucose range considered normal and without a cutoff glucose level for clear risk, Dr. Metzger said at the American Diabetes Association meeting.

These findings, he said, contributed to a growing consensus that treatment criteria may need to be reevaluated. A consensus group is to meet by May 2008 to determine at what point the risk reaches clinical significance.

"There is no one standard that exists currently" for screening and diagnosis of gestational diabetes, Dr. Metzger said. "There certainly will be some changes."

"We are not making the decisions on arbitrary values as has been done in the past," he added.

To clear up such questions, Dr. Metzger and colleagues undertook the seven-year, 23,325-woman, multinational Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study.

The women underwent an oral glucose tolerance test and fasting plasma glucose measurement at around 28 weeks' gestation. To avoid bias, the results were blinded. Women with high glucose levels requiring treatment were removed from the study according to prespecified criteria.

Maternal blood samples were measured for serum C-peptide and HbA1c. Cord blood was measured for serum C-peptide and plasma glucose at delivery, and neonatal plasma glucose was also measured at one and two hours after delivery.