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March 7, 2001
Gestational Diabetes on the Rise Managing the risk of diabetes in pregnant women and their babies

By Sharon Linsker

Brian Yanish

first letter last year, when she was in her third trimester of pregnancy, Michelle Ehrlich* was often thirsty, and she had trouble seeing. Probably just contact lens problems, she thought. Then one day she was suddenly unable to tell whether the traffic lights were green or red. Within 24 hours, tests showed Ehrlich, 27, had blood sugar levels so high that they could have led to diabetic coma.

Diagnosed with gestational diabetes mellitus (GDM), Ehrlich was referred to Columbia-Presbyterian Medical Center, in New York City, where her doctor brought her blood sugar levels under control. Five weeks later she went into early labor, giving birth to a healthy baby girl.

In gestational diabetes, a form of type 2 diabetes that's on the increase, the body does not properly use all the insulin it makes. Pregnant women who have never had diabetes before but who have high blood sugar levels during pregnancy are said to have GDM.

Insulin resistance

Pregnancy demands more insulin in the body than normal because of the increased production of hormones; this imbalance can lead to insulin resistance. According to the American Diabetes Association (ADA), women in one or more of the following categories are at increased risk for gestational diabetes:

  • 25 years or older
  • Overweight prior to pregnancy
  • Family history of type 2 diabetes
  • Hispanic, African American, Native American, Asian, or Pacific Islander

Gestational diabetes affects the mother late in the pregnancy; therefore, women who are at risk should be screened between the 24th and 28th weeks -- around the sixth month.

When this illness is left untreated or is poorly controlled, a woman's blood sugar levels remain high. Extra blood sugar crosses the placenta, giving the baby high blood sugar levels as well. The problem can lead to having an overweight baby -- a condition called macrosomia -- which can cause damage to the baby's shoulders during birth. Newborns whose mothers have untreated GDM are at risk for breathing difficulties and other problems. What's more, these babies may become children who are at risk for obesity and adults who are at risk for type 2 diabetes.


When GDM is not treated or is poorly controlled, a woman's blood sugar levels remain high. Extra blood sugar crosses the placenta, giving the baby high blood sugar levels as well.


The good news, however, is that mothers with GDM can give birth to healthy babies. "The illness is eminently treatable, especially when it's caught early and meticulously managed," says Robin S. Goland, M.D., co-director of the Naomi Berrie Diabetes Center at Columbia-Presbyterian. She recommends that whenever possible, women with GDM be in the care of an obstetrician and an endocrinologist, along with a nutritionist or a diabetes educator.

Family support

Treatment for GDM is highly individualized. "Each case must be individually managed because each woman's insulin requirements are different," says Dr. Goland. Because treating GDM requires a major lifestyle change, the Naomi Berrie Diabetes Center likes to involve other family members in education and care. Indeed, support from relatives is a plus when a woman is changing exercise and eating patterns, monitoring blood sugar, and taking insulin.

While Dr. Goland reports that nearly all the babies born to GDM patients at the Naomi Berrie Diabetes Center are healthy, she is seeing some alarming patterns. She observes a decrease in the age at which people get type 2 diabetes, an increase in the number of people with type 2 diabetes -- and an increase in the number of adolescents whose mothers had gestational diabetes. "So it's a vicious cycle, with more diabetes leading to more babies at risk," she says.

This pattern has been seen across the country. In 1988 the American Diabetes Association estimated that 135,000 women -- or 4 percent of all pregnant women in the United States -- were diagnosed annually with gestational diabetes. But in its position statement this year, the ADA upped the figure to 200,000 -- or 7 percent of pregnant women.

What has led to the increase? "Because diabetes is a genetic illness, people inherit the tendency to have GDM. But environmental issues, such as our decreasing level of activity and our increasing level of obesity, bring it out," explains Dr. Goland.

Stressful discoveries

While experts consider obesity a major cause of the increase in GDM, not every woman with GDM is overweight. Ehrlich, who gave birth last year, is of average weight. So too is Myrna Scott, 32, another patient at the Naomi Berrie Diabetes Center.

Gestational Diabetes Among the Pima Indians

To understand the role environmental factors likely play in GDM, consider the case of the Pima Indians of Arizona. Among ethnic groups in the United States, they have the highest rates of type 2 diabetes; about half the population age 35 or older are affected.

From 1978 to 1998, David J. Pettitt, M.D., now a senior scientist at the Sansum Medical Research Institute, in Santa Barbara, California, studied the serious consequences of diabetes in pregnancy in this Native American group. "One characteristic of the Pima Indians is that they tend to be very obese -- even as young children," says Dr. Pettitt. And since obesity is a risk factor for diabetes, being overweight sets the type 2 cycle in motion.

But it wasn't always that way, says Dr. Pettitt. For 2,000 years, the Pima Indians subsisted by farming -- a way of life that was inherently physically active. Even 100 years ago, there were few reports of obesity among this group, nor was diabetes a problem. But since the 1950s, the Pima have led an increasingly sedentary lifestyle, and their diet has shifted -- with these changes have come a vast increase in diabetes. While dietary and lifestyle shifts have occurred in other groups, the Pima Indians have been affected by type 2 diabetes far more than the rest of the population. "We must conclude that a century ago -- and probably 2,000 years ago -- the genetics were similar but the environment was not conducive to type 2 diabetes," he reports.

Looking back, Scott, a critical care nurse, says she should have known something was wrong, but her symptoms were those of many other pregnant women. She was often very tired and she experienced palpitations after eating a large meal.

But after moving from London to New York City, Scott finally had her blood sugar levels tested. Doctors found that Scott, in her 32nd week of pregnancy, had elevated levels -- a sure sign of gestational diabetes.

Scott says her first reaction was shock. And she was angry the illness hadn't been detected by her doctor in London, where routine testing is not the norm. "I was also fearful I had hurt my baby," says Scott. "Overall, I went through a few days of feeling incredibly sorry for myself. Here I was on maternity leave -- a time at the end of pregnancy when you're supposed to put your feet up and eat chocolates."

Instead of being able to relax, she's had to be vigilant to keep her blood sugar levels under control. For her, that means following a rigid diet, weighing and measuring portions, testing her blood sugar six times a day, and injecting herself with insulin three times a day.

Now in her 39th week of pregnancy, Scott says that the burden of her illness has been eased by the team at the Naomi Berrie Diabetes Center. "I find the level of care very reassuring," she says.

What happens to women with GDM after giving birth? Most women return to normal blood sugar levels. But the chances are two out of three that a woman who has had GDM will be affected in later pregnancies. And approximately 40 percent of women with gestational diabetes who are obese before pregnancy develop type 2 diabetes within four years, says the ADA. "And that's where being followed by a diabetes team continues to be important," says Dr. Goland, who stresses the value of preventive health care.

* The patient's name has been changed.

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