A lower cut-point for diagnosing gestational diabetes is a double-edged sword for clinicians.

Adopting more stringent criteria would triple the number of women identified whose abnormal glucose levels could potentially endanger their health and that of their unborn children. Once diagnosed, they could be treated.

But adopting the proposed criteria would skyrocket the number of diagnosed gestational diabetes cases from about 135,000 to more than 500,000 each year, according to Dr. E. Albert Reece, dean of the University of Maryland School of Medicine, Baltimore.

"It’s quite possible that lowering the diagnostic threshold with these criteria could push the incidence of gestational diabetes from about 7% of all pregnancies to more than 20%," Dr. Reece said in an interview. "With that may come the potential for more cesarean sections and their related adverse consequences. It’s not a case of simply diagnosing earlier – it’s diagnosing earlier with a real potential for increased interventions that bring along their own risks."

The American Diabetes Association adopted the new diagnostic criteria last year (Diabetes Care 2011;34:S11-61). Now, the American College of Obstetricians and Gynecologists is contemplating its own move, and Dr. Reece, a well-respected expert on the topic, is urging caution.

If ACOG were to adopt the criteria, he said, obstetric interventions related to the condition would almost certainly rise. Mothers and babies would be at the most direct risk of any additional procedures, but clinicians will face their own set of problems.

As cesarean sections and other invasive procedures increase, lawsuits go up as well. The possibility of these collateral consequences isn’t the only thing to consider, warned Dr. Reece. Even now, clinicians who care for women with gestational diabetes are hard pressed to keep up with their patient load, let alone the tens of thousands more who would be diagnosed under the new criteria.

Associated costs can’t be ignored either, he said, especially at this crucial time in America’s health care history, when affordable care for everyone is now the law of the land.

In theory, the idea of catching more cases earlier seems sensible. But health care policy should rely on more than theory, said Dr. Reece, who is also the John Z. and Akiko K. Bowers Distinguished Professor of Obstetrics and Gynecology at the university.

"If we could be certain that making this diagnosis earlier would actually improve outcomes, we would have a compelling reason to change. But at this point, many are unconvinced that change would result in improved outcomes."

The current diagnostic threshold for gestational diabetes is a positive result on two or more oral glucose tolerance tests, with glucose levels of more than 180 mg/dL at 1 hour; more than 155 mg/dL at 2 hours; and more than 140 mg/dL at 3 hours. This approach is based on data gathered in the 1970s and 1980s.

More recent data from the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study Cooperative Research Group suggest that subclinical hyperglycemia affects additional thousands of pregnant women. The study found positive associations between maternal hyperglycemia and increasing rates of large for gestational age neonates, evidence of fetal hyperinsulinemia, neonatal hypoglycemia, and cesarean delivery.

After the study was published in 2008, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) published its new recommendations for the diagnosis and classification of hyperglycemia during pregnancy. Under the new system, gestational diabetes can be diagnosed after a single abnormal oral glucose tolerance test with the threshold of fasting plasma glucose of more than 92 mg/dL, or, after a single oral test, a level of more than 180 mg/dL at 1 hour and more than 152 mg/dL at 2 hours.

"A key argument for changing the current diagnostic guidelines for gestational diabetes in the United States is that a single diagnostic test – by eliminating the screening phase – will be more convenient for the provider and the patient," Dr. Reece wrote in the October issue of the American Journal of Obstetrics and Gynecology (2012 [doi: 10.1016/j.ajog.2012.10.887]). "Furthermore, because it is more user-friendly, it is argued that the one-step diagnostic test also will be much easier to administer and, thus, the earlier diagnosis and treatment of gestational diabetes will lead to more consistent care, better organized research, and, ultimately, to better outcomes for mothers and their babies."

According to the American Diabetes Association, up to 10% of women with gestational diabetes have underlying undiagnosed diabetes, usually type 2. Women who develop gestational diabetes without underlying disease have a 35%-60% chance of developing it over the next 10-20 years.

Studies also are beginning to uncover long-term risks for babies who develop during a hyperglycemic pregnancy. These infants appear to have double the risk of developing childhood obesity and/or metabolic syndrome, laying the foundation for adulthood rife with obesity- and diabetes-related health problems.

But when researchers examine the overall effect of a more stringent screening and diagnostic protocol, the view is somewhat cloudy, Dr. Reece said.

A 2011 study found that treating mild gestational diabetes was a cost-effective way of improving maternal and neonatal outcomes, including decreasing preeclampsia, cesarean sections, macrosomia, shoulder dystocia, permanent and transient brachial plexus injury, neonatal hypoglycemia, neonatal hyperbilirubinemia, and neonatal intensive care unit admissions (Am. J. Obstet. Gynecol. 2011;205:282.e1-7).

But a more recent study found that treating the condition only saves money when considering the mother’s long-term health.

"Our model demonstrates that [the new criteria] are cost-effective only when post-delivery care reduces diabetes incidence," wrote Dr. Erika Werner.

"When post-delivery care was not accomplished, the ... strategy was no longer cost-effective. ... Although there are potential perinatal benefits associated with the [criteria], these benefits alone do not justify the additional cost associated with tripling the number of GDM diagnoses in the U.S.," the authors wrote (Diabetes Care 2012;35:529-35).

The criteria’s biggest financial bang would come from their ability to detect occult diabetes in the mothers, Dr. Werner said in an interview.

"It would allow us to differentiate those women with underlying diabetes from those with only gestational diabetes. We’re missing these women now because very few ever come back for their postnatal diabetes screening," said Dr. Werner, a maternal fetal medicine specialist at Johns Hopkins University, Baltimore. Intervening early can be assumed to save much of the long-term financial costs of type 2 diabetes.

Her cost analysis isn’t set in stone, though, because it couldn’t control for the financial impact of either increased perinatal interventions – like cesarean sections – or the financial impact of preventing fetal consequences. And there’s no way to predict how many women who did develop diabetes postnatally would require insulin or oral medications, and how many could be conservatively managed with diet and exercise.

"We didn’t control for this because there are not data telling us that controlling glucose in pregnancy improves outcomes for women and neonates. The trends are there, but the confidence intervals are not. Any cost analysis is limited by the data that are out there. And in this case, we need more data," she said.

Dr. Reece agreed, saying only large long-term studies could provide enough of the evidence necessary to support changing the diagnostic algorithm.

But, Dr. Werner said, U.S. physicians might be able to learn from their international colleagues. "Some countries are already moving forward with them, and that will give us some of the additional data that we’re looking for."

Australia is one of those countries. The Australasian Diabetes in Pregnancy Society (www.adips.org) adopted the diagnostic criteria earlier this year, said Prof. Robert Moses, director of the Illawarra Diabetes Service in Wollongong, New South Wales. In a March editorial in the journal Diabetes Care, he likened the controversy over the recommendation to "opening Pandora’s box," adding that he supports the change, but that it needs to be thoughtfully applied, in a "clinically responsible way" (2012;35:461-2).

The change is expected to bump up Australia’s gestational diabetes incidence from 10% to 13%, Dr. Moses said in an interview. Any increase in the cost of managing these women and their pregnancies pales beside the clinical alternative.

"The cost of diagnosing and treating women with gestational diabetes is relatively little compared with other health costs. However, there are unfortunately a lot of potential add-on costs. We know that women with gestational diabetes have more interventions, both obstetric and pediatric."

Even considering those costs, ensuring the long-term health of these mothers and babies is a good investment, he said. To put the cost in perspective, "One course of experimental cancer therapy is likely to cost more than testing 1,000 women and treating the 130 with gestational diabetes. It is all a matter of perspective and priority."

He’s glad that Australia chose to move ahead with the change rather than wait for the official numbers to prove that it works.

"Large studies are difficult to initiate and fund. At some stage, common sense has to prevail. Waiting for the results of trials which will not happen in our lifetime should not be an excuse not to give the best possible maternal and fetal care. This is too important a problem to ignore, especially as the solution is relatively simple and the cost is relatively trivial," he said.

None of the sources named disclosed any financial relationships relative to the topic of this article.

New Criteria for Gestational Diabetes Could Swamp Providers