Apparent Sharp Rise in Gestational Diabetes No Cause for Alarm

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Rates of gestational diabetes in the U.S. appeared to rise sharply in recent years, according to a new study that appeared in the Journal of the American Medical Association (JAMA). 

If you are pregnant now or hope to become pregnant soon, that finding may set off alarms for you, but the situation isn't that dire. 

"The researchers found that gestational diabetes had gone up a lot for women of all ages and all ethnic backgrounds," says Rajesh Kumar Garg, M.D., an endocrinologist and the director of the Comprehensive Diabetes Center at the University of Miami Health System.

"They observed that in 2011, the disease affected 48 out of 1,000 live births," Dr. Garg says. "But by 2019, that had increased to about 64 out of 1,000 births, which sounds really troubling," 

Moving the diagnostic goalposts 

The JAMA study has a back-story, Dr. Garg says. "That finding of a big spike reflects a recent change in the testing method and the blood sugar levels at which experts diagnose gestational diabetes," he said.

This change dramatically expands the number of people seen as having the problem, he adds. Many doctors believe that the changes are not needed or helpful. 

 The uptick in gestational diabetes during the years of the study might not look so dramatic if the previous blood sugar levels were still being used, he says. 

What happened? One test replaced two. 

In 2010, a leading group of medical experts called the International Association of Diabetes and Pregnancy Study Group proposed changes in the testing method and glucose levels that doctors would use to diagnose gestational diabetes, Dr. Garg says. 

Experts use glucose tolerance tests to diagnose gestational diabetes, among other problems. For the tests, a person drinks a solution that includes glucose, and then they test blood samples to see how fast the glucose leaves their blood and enters other cells.

Before the change, doctors diagnosed gestational diabetes by giving a patient two such tests, and the second test would be used to confirm the first reading. "After the change, only one test was required," Dr. Garg says. 

gestational diabetesThe newer diagnostic approach also lowered the thresholds for blood glucose levels. 

While the older method required a fasting glucose level of 95 mg/dl or higher for a diagnosis, the newer approach lowered the cutoff to 92 mg/dl. 

"That may sound like a slight difference," Dr. Garg says. "But in fact, that change can greatly expand the population of expectant people who are told that they have this problem."

Combined, these changes can and have significantly increased the number of people hearing from their doctors that they have gestational diabetes, as described in the recent JAMA article.

Experts don't all agree.

The American College of Gynecologist and Obstetricians (ACOG), the leading organization for such doctors, did not accept the new guidelines. Most patients with gestational diabetes are diagnosed by their obstetricians, Dr. Garg says. "The fact that the American College of Obstetricians and Gynecologists recommends that we use the old guidelines is very important," he says. 

Most doctors who care for pregnant women also heed the guidance from the American Diabetes Association (ADA), Dr. Garg says. "The ADA briefly recommended that doctors follow the new guidelines, "he says. "But after a few years, the ADA changed its guidance and told physicians that they could follow either the older or the newer guidelines." 

When the new diagnostic criteria were first published, he and some colleagues had heated debates about their value. In the end, the UHealth team chose to keep using the earlier cutoff levels. 

More patients mean more treatment.

If all physicians were using the new blood sugar levels for diagnosis, there would be a significant increase in the number of patients told they have gestational diabetes. "In modern medicine, sometimes researchers end up inflating the number of diseased people before proving the benefits of treating them." 

 "When you expand the patient pool, you increase the cost of health care. That may be profitable for industry, but it's not necessarily better for patients," Dr. Garg says. 

Gestational diabetes has indeed been increasing.

Older women are at much higher risk for gestational diabetes, and, for decades, the trend in the U.S. has been for women to postpone childbearing. In fact, pregnancies that occur in a person's late 20s tend to be healthier overall than pregnancies that occur in the 30s or 40s, he says. 

Delaying pregnancy heightens the risk for several different complications, not just gestational diabetes," Dr. Garg says. "Meanwhile, women are becoming busier and busier in their work lives, which are important, and pregnancy is often delayed."

Putting off having children until their 30s to develop a career used to be a choice made mostly by upper-middle-class women, but that's no longer true, research shows. Now, postponing pregnancy to achieve greater workplace success is a choice made by women of all backgrounds and income levels. This means more women are becoming pregnant when their risk for gestational diabetes is higher. 

Your weight matters too.

Excess weight represents a major risk factor in this realm. "Rising rates of obesity that we've seen for decades have been contributing all along to rising rates of all kinds of diabetes," Dr. Garg says. These include gestational diabetes.

The increase in gestational diabetes that reflects postponed childbearing and being heavier is a true upward shift, he says. It's quite different from the spike that came when some researchers changed the approach to diagnosis. 

The basic problem in all forms of diabetes

Diabetes arises when your blood sugar (glucose) levels climb too high. Normally, your body uses a hormone made in the pancreas, insulin, to transfer glucose, coming from your food, from your blood into your body's cells to provide energy.

"If you have too little insulin or resistance to insulin action, then glucose may remain in your blood. This denies your cells the energy that they need to do their various jobs," Dr. Garg explains. Eventually, this can cause many serious health problems. 

What's different about gestational diabetes?

Gestational diabetes is a form of illness that occurs late in pregnancy. "By definition, gestational diabetes occurs in the third trimester," Dr. Garg says. "If it gets detected sooner than that, it is more likely a case of type 1 or type 2 diabetes that had not been diagnosed before the pregnancy." 

Between 2% and 10% of pregnancies in the US involve gestational diabetes, according to the Centers for Disease Control and Prevention. The condition demands careful management to assure the best possible outcomes for both mother and baby. 

"Today, best practice in obstetrics care involves all pregnant people being screened for gestational diabetes at week 24 or shortly after," Dr. Garg says. Such screening is in line with guidance from the U.S. Preventive Services Task Force (USPSTF). 

The USPSTF is a group of experts who issue guidelines designed to keep people healthy by preventing disease rather than treating sickness once it occurs, which is the focus of most medicine in the US.

What happens if gestational diabetes isn't managed well?   

"If a woman develops gestational diabetes, it raises her risk and also her child's risk for winding up with many other bad outcomes," Dr. Garg says. The condition heightens the risk of premature birth, which can cause breathing and other serious problems. 

 "Gestational diabetes also increases a pregnant person's risk of developing high blood pressure," Dr. Garg says. High blood pressure, in turn, increases the risk of stroke and for labor to need to be induced, among other complications. 

Gestational diabetes also increases a woman's risk of having metabolic abnormalities, he explains. These include excess body fat around the waistline, high cholesterol levels, and high blood sugar. 

Women with gestational diabetes tend to have large babies, which weigh 9 pounds or more, Dr. Garg says. This means that delivery often happens through a cesarean section (C-section). 

"(Larger babies) often have more difficult deliveries," he says. "And as they grow into adulthood, they also tend to have more metabolic abnormalities." 

 What does treatment involve?

It's rarely difficult to treat gestational diabetes, Dr. Garg says. "Eighty to 90% of the time, we can control the condition without medication. In most cases, changes to the diet and increased physical activity will usually suffice to restore healthy blood sugar levels." 

"For the other 10 to 20% of women, we do use insulin, but the regimen that we prescribe is not that hard to follow," he says. It may suffice for many women needing treatment to test their glucose levels three times a day and inject insulin once a day. Very few women need multiple insulin injections and testing blood sugar several times a day.

Gestational diabetes raises your risk for type 2 diabetes

If you have gestational diabetes, you're at high risk of developing type 2 diabetes after birth, Dr. Garg says. "Getting down to a healthy weight and staying there after the delivery can reduce your risk for this problem," he says. 

Anyone who had gestational diabetes also should have their blood sugar levels checked at six weeks and at 12 weeks postpartum. Then do it again every 1 to 3 years going forward, according to current guidelines for care. Continuing to have your blood sugar levels checked as you grow older matters, as the risk for type 2 diabetes rises with age. 

Breastfeeding seems to decrease the odds that a woman who has gestational diabetes will develop the type 2 form of the illness. 

"Breastfeeding also delivers a long list of benefits to both mother and baby," Dr. Garg says. "If you can, breastfeed." 

Prevention is always better than cure

If you're not pregnant yet, but you plan to become pregnant, try to reach a healthy weight before you conceive, obstetric experts advise. Doing so will not only reduce your risk for gestational diabetes, Dr. Garg says, it will reduce a host of other problems that can affect your pregnancy. 

Women who are at a healthy weight have fewer miscarriages and stillbirths, Dr. Garg notes. "They're also at lower risk for having a complicated vaginal delivery," he says. "And they're less likely to need a C-section, which sometimes leads to wound infections."

Your pre-pregnancy body mass index (BMI) will affect recommendations for pregnancy weight gain. 

If your BMI falls at or above 30, your health care provider will probably suggest keeping your weight gain to 11 to 20 pounds.

Prepare and plan

Consult your healthcare provider and read about steps towards a healthy pregnancy at the National Institutes of Health

"Remember," says Dr. Garg, "Healthy pregnancies bring healthy babies, with the best possible start for a healthy, good life."


Milly Dawson is a contributing writer for UMiami Health News.


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