Gestational diabetes mellitus (GDM), or high blood sugar during pregnancy, used to be relatively rare, occurring in about 3 percent to 4 percent of pregnancies. But in recent years, the rate has doubled— now, up to 6 percent to 8 percent of moms-to-be are diagnosed with this prenatal complication. And new recommendations lowering the cutoff point for diagnosis may lead to an even more dramatic increase.
If these new guidelines from an international panel of 50 experts are adopted in the United States, 16 percent of pregnant women may hear the words, “You have gestational diabetes.”
In women with GDM, excess glucose (blood sugar) passes from the mother’s bloodstream through the placenta. Serious pregnancy complications include preeclampsia (a serious high blood pressure condition that can be fatal), preterm delivery and delivery of overweight babies, often via Cesarean section. Some 70 percent to 80 percent of women diagnosed with GDM in the United States eventually develop type II diabetes.
New research is showing that GDM can have long-term consequences for children as well. “Children of women with GDM are at risk for developing type II diabetes themselves,” says Danielle Downs, Ph.D., an associate professor of kinesiology and obstetrics and gynecology at Pennsylvania State University who conducts research on gestational diabetes. But even normal-size babies who are born to mothers with untreated GDM are at greater risk of becoming overweight kindergarteners—and, consequently, overweight adults.
Although being overweight is a major risk factor for GDM, only about half of women diagnosed with it carry excess pounds. Age is also a factor—women age 25 and older, but especially older than 35, are at greater risk—and genes play a role: You can be healthy and lean and still develop GDM because of a genetic predisposition or other factors.
Lowering the Threshold
Currently, women in the United States routinely undergo a GDM screening between 24 weeks and 28 weeks of pregnancy. At your doctor’s office, you drink a bottle of super-sweet soda—think Mountain Dew spiked with pancake syrup—and an hour later, your blood is drawn.
If your blood sugar is higher than 140 milligrams of glucose per deciliter of blood plasma (mg/dL), you are referred to a laboratory for an oral glucose tolerance test (OGTT). This one involves an overnight fast, then drinking a soda that’s monumentally sweeter than the first one and having blood drawn four times over three hours. If your blood sugar exceeds a designated threshold at two of the four blood draws, you are diagnosed with GDM.
This process will change significantly if the international panel’s recommendations, under consideration by the American Diabetes Association and The American College of Obstetricians and Gynecologists, are adopted in the U.S., as they have been in Japan. The doctor’s office screening will be dropped, and all pregnant women will undergo a two- hour, three-blood-draw version of the OGTT, including the overnight fast but requiring a smaller amount of glucose-sweetened beverage.
If the results of just one of the three blood draws exceed a threshold that is slightly lower than the current numbers, GDM will be diagnosed.