But who should receive treatment? Despite the new research, there's no consensus on the threshold for gestational diabetes or even whether mild cases warrant intervention. "We don't know the level of glycemia [high blood sugar] that truly poses a risk to the fetus," says Mark Landon, M.D., vice chairman of the department of OB/GYN at Ohio State University Medical Center in Columbus, who is studying the effectiveness of treating mild GDM.
The world's top gestational diabetes researchers will convene later this year to analyze the research and possibly lower the blood-sugar levels that indicate a diagnosis. "There's a good chance [lowering the threshold] will result in more women being identified," says Boyd Metzger, M.D., a professor of medicine and endocrinology at Northwestern University and lead investigator of a GDM study involving 23,000 pregnant women in nine countries.
"We found that some problems occurred even in ranges previously considered normal for pregnant women," he adds. Among Metzger's results: moms-to-be with the highest blood-sugar levels were four to six times more likely to deliver large babies than women with the lowest levels.
It's not just babies who may be affected over the long term. Among women diagnosed with GDM, 50 percent will develop type II diabetes within 5 to 8 years; 70 percent to 85 percent will develop the disease during their lifetimes, Metzger says. A GDM diagnosis can serve as an early warning, motivating at-risk women to make permanent lifestyle changes. "Even if treatment only delays diabetes by 10 or 15 years, that's huge," he says.
Limiting sweets and eating smaller, more frequent meals and more fruits and vegetables, is typically the first line of treatment, but exercise can help. Downs is researching how much and what type of physical activity works best. Though gestational diabetes is often associated with overweight, sedentary women, she notes that only 50 percent to 60 percent of women diagnosed with GDM are overweight. Age is a factor—women over age 25 are at greater risk due to declining pancreas function—and there's a big genetic component.
"You could be healthy, thin and still get GDM because of a genetic predisposition," says Downs, noting that "Bachelorette" Trista Sutter was forced to deliver a month early partly because of complications due to gestational diabetes. Downs herself, a marathon runner with a family history of diabetes, came within two blood-sugar points of a GDM diagnosis during her first pregnancy at age 31. In her second pregnancy, she passed the screening tests with flying colors, attributing her better blood-sugar levels to "being more stringent with my diet and maintaining a moderate-intensity exercise plan."
More than 75 percent of women who "fail" the one-hour glucose challenge, as I did, end up passing the three-hour glucose-tolerance screening, the one with the unbearably sweet soda. I didn't have gestational diabetes, but the testing experience was a reminder to keep cranking on the elliptical trainer and eating my vegetables.