Pregnant women of colour more likely to be diagnosed with gestational diabetes

An image of two pregnant women. (cottonbro studio/pexels.com)

Being diagnosed with gestational diabetes during pregnancy can put a damper on what may otherwise be an exciting time for a blooming family.

It’s a serious condition that must be diagnosed, doctors say, to avoid complications for mom and bub in the future.

All the same, they admit the test is far from perfect.

“Gestational diabetes traditionally refers to any pregnant person in whom abnormal glucose tolerance was recognized,” explains Dr. Gabrielle Cassir, a maternal-fetal medicine specialist with McGill University. “It really develops because of certain functions in certain cells in the pancreas that are just insufficient to overcome the insulin resistance associated with the pregnant state.”

In Canada, 7.9 per cent of pregnant women are diagnosed with gestational diabetes.

Globally, that number goes up to 17 per cent, hovering around 10 per cent in North America and increasing to 25 per cent in south-east Asia.

Cassir points out that there are multiple risk factors that could lead to a positive diagnosis, such as age (especially those 35 and older), a family history of diabetes or other medical conditions and pre-pregnancy obesity.

“Then, there’s the whole component of just certain ethnic groups,” she said. “There are certain groups which have a higher prevalence of type two diabetes. We’re talking about Hispanic, Native American, Alaskan, those who are Native Hawaiian, south or east Asian.”

How does the test work?

Doctors will generally test all their pregnant patients, and screening can vary around the world.

In Canada, there is a two-step approach, with the first including a mom-to-be drinking a 50g glucose tolerance drink.

“You don’t necessarily have to be fasting for the test, but I always tell my patients don’t have a bowl of Lucky Charms or something right before,” Cassir said.

The patients are then categorized into different zones.

“You have a lower limit, which kind of excludes the diagnosis, and then you have an upper limit which confirms gestational diabetes,” said Cassir.

Anyone in the grey zone, with results between 7.8 and 11.1, gets signed up for step two: a 75 g glucose tolerance test.

“If you fail one of those tests, that’s when you get diagnosed with gestational diabetes,” she said.

A woman diagnosed with gestational diabetes will then be closely monitored to avoid potential risks.

“Increased surveillance, increased visits, a visit with a nutritionist, endocrinologist, increased ultrasound frequencies,” Cassir lists.

Doctors will generally recommend that patients be induced between 39 and 40 weeks, depending on whether they are being treated with insulin or not.

“There’s a higher, increased risk of preeclampsia, or large-for-gestational-aged babies,” Cassir said. “There’s a higher incidence of cesarian births and all their associated morbidities.”

Risks for mom and baby

Post birth, babies of mothers diagnosed with gestational diabetes will undergo some testing as “there are a few risks that the baby has inadvertently when mom has gestational diabetes.”

Some of these include hypoglycemia (low blood sugar), hyperbilirubinemia (or jaundice) and hypocalcemia (low calcium levels).

“They also have a higher incidence of respiratory distress and even certain cardiac problems that can be associated depending on the levels of diabetes in pregnancies and the levels of glucose,” Cassir said. “Typically, it’s really to make sure that their sugar levels are OK.”

Mom will also have to undergo some testing.

“Glucose levels usually come back into normal ranges quickly enough after delivery, but it is always important six weeks to three months after delivery to repeat your sugar test,” Cassir said. “We usually recommend a follow up with the family physician, at least on a yearly basis, to make sure that we have some type of screening for later in life type two diabetes.”

Why women of colour?

Dr. Kaberi Dasgupta, a professor of medicine and director of the division of general internal medicine (GIM) at McGill University, adds a positive diagnosis is sometimes inevitable.

“There’s always going to be some people who do all the right things, you know, are active, are eating well, and still get gestational diabetes,” she said.

She calls the gestational glucose tolerance test a “stress test” that a person cannot really “fail.”

“The diagnosis of gestational diabetes was originally sat with the notion of what’s the likelihood of developing type two diabetes later on?” Dasgupta explains.

She points out that every time the threshold is adjusted, more or fewer people get diagnosed accordingly.

“You have to set a cut point somewhere, and to say where the cut point is, is where the risk appears to be,” she said. “There are a lot of people that could have difficulties at that cut point, but that’s a constant source of debate, definitely in the gestational diabetes world.”

One of the reasons why a person could be susceptible to a diagnosis depends on where their family is from.

“In Asian countries, people with higher sugars during pregnancy are the ones that are more likely to have type two diabetes later on,” Dasgupta explains. “If we set white people as the reference, Asian-origin people are less likely to develop the complications, and South Asian-origin people and Black people are more likely to develop the complications.”

She says differences based on ancestral background are just as important as biology and social conditions – that is, the history of an area, speed of urbanization and more.

“The biggest one for the Black population is, one of the issues that’s been raised is, there’s been that history of colonization and slavery and stressors,” Dasgupta said. “We know that those major kinds of stressors can change how our bodies handle different things.”

She says what occurs during those moments of intense pressure is an epigenic change.

“Irrespective of your genes, your body will start to develop in a way that is more efficient at taking in calories and taking in sugar,” she said.

These cellular modifications, Dasgupta says, can last for generations.

“That’s been one of the explanations for any country that’s had major colonialism, war, conflict,” she said. “We like to separate our biology from social circumstances, but they’re very intertwined, and they can remain intertwined for generations.”

Another factor? We’re more sedentary than ever before.

“There are people who, they’re going to eat fast food and Uber all the time,” she said. “Then there’ll be other people, they’re cooking everything, but they’re cooking everything the way their grandma did and so, there’s way too much starch.”

Despite current-day widespread immigration, Dasgupta says she wouldn’t necessarily advise changing the gestational diabetes threshold – because it can never be perfect.

“I don’t think that we could confidently say that we could adjust the diagnostic threshold based on background but maybe, and this is a big maybe, one could imagine a world where you would adjust the concerns based on what else is happening,” she said. “We’re not there yet.”