New research from Yale University School of Medicine scientists shows that children exposed to gestational diabetes in the wombs of their mothers are nearly six times more likely to develop diabetes or prediabetes than children not exposed. The study, led by Dr. Sonia Caprio and colleagues, is published in Diabetologia, the journal of the European Association for the Study of Diabetes.
Gestational diabetes (or gestational diabetes mellitus, GDM) is a condition in which women without previously diagnosed diabetes exhibit high blood sugar (glucose) levels during pregnancy (especially during their third trimester). Women who develop diabetes during pregnancy are at an increased risk for a number of serious complications, including preterm birth, emergency caesarean delivery, and preeclampsia.
Additionally, exposure to gestational diabetes in utero has been shown to negatively impact fetal and infant health, raising the risk of respiratory distress syndrome, hypoglycemia, and other perinatal complications. The condition is also associated with an increased risk of fetal and neonatal death.
Recent data show that the rate of gestational diabetes is on the rise, increasing by 10-100 percent in several racial/ethnic groups over the past 20 years, paralleling the rise in obesity. While the true prevalence of gestational diabetes is unknown, research indicates that nearly 1 in 10 pregnant women in the U.S. will develop the condition.
With the increase in gestational diabetes, there is a growing need to understand the effects of glucose exposure on the newborn in the womb, at birth and later in life. The risk of developing impaired glucose tolerance (IGT) (prediabetes) in individuals exposed to diabetes in the womb has not, say the authors, been adequately investigated.
Thus in this new study, the authors examined the risk in obese youths of developing IGT after exposure to gestational diabetes in the womb.
‘Exposure to gestational diabetes was the most significant predictor of … childhood prediabetes and diabetes’
The researchers hypothesized that “prenatal exposure to gestational diabetes in obese children with normal glucose tolerance (NGT) would be associated with development of altered glucose metabolism over time, driven by an impairment of beta cell secretion relative to the insulin sensitivity.”
A total of 255 obese adolescents with a normal glucose tolerance were selected for the study. All of them were investigated for in utero exposure to gestational diabetes and underwent an oral glucose tolerance test, which was repeated after approximately 3 years.
Overall, the researchers found that 210 (82 percent) participants were not exposed to gestational diabetes (called the NGDM group), and 45 (18 percent) were exposed to gestational diabetes (the EGDM group).
Among those participants who were not exposed to to gestational diabetes (i.e., the NGDM group), only 9 percent (n=18) developed either IGT or type 2 diabetes compared with 31 percent (n=14) of participants who were exposed to gestational diabetes (i.e., the EGDM group) who developed either IGT or type 2 diabetes, with both results statistically significant.
“Exposure to gestational diabetes was the most significant predictor of developing IGT or type 2 diabetes, with an increased risk of almost six times for those children exposed to gestational diabetes in the womb,” the authors report.
The need for research on prenatal exposure to gestational diabetes ‘has never been more urgent’
At baseline, the EGDM group showed a reduction in beta cell function (the cells that produce insulin); at follow-up, they also displayed a reduction in insulin sensitivity compared with the NGDM group.
Children born to mothers with gestational diabetes are nearly 6 times more likely to develop prediabetes and diabetes themselves, the study found.
“Our study demonstrates that obese normal-glucose-tolerant children of mothers with gestational diabetes have pre-existing defects in beta cell function,” say the authors. “This is in turn a strong risk factor for these children to develop prediabetes or diabetes.”
The authors warn that the “ever growing number of women with gestational diabetes suggests that the future will be filled with children with early diabetes at a rate that far exceeds the current prevalence.”
The researchers recommend that obese children of mothers with gestational diabetes undergo routine screening for prediabetes and/or impaired fasting glucose (another form of prediabetes) starting in adolescence. They also strongly advocate for the use of preventive and therapeutic strategies before the development of full clinical manifestation of diabetes, which is far more difficult to manage.
“While we cannot use this analysis for development of definitive screening guidelines, we strongly suggest that, among obese children and adolescents exposed to gestational diabetes, specifically if additional risk factors are present – such as severe obesity or being of ethnicity minorities at higher risk – oral glucose tolerance tests should be performed at baseline (specifically in mid-pubertal adolescents) and potentially repeated based on clinical judgement,” the researchers write.
Future research should focus on the underlying mechanisms responsible for the high incidence of diabetes among children exposed to gestational diabetes, the team says, adding: “The need for studies aimed at unraveling the role of genetic or epigenetic factors and environmental postnatal factors that might be causing functional defects in the beta cell has never been more urgent.”
These new findings come just as the Centers for Disease Control and Prevention (CDC) released a new report showing that 40 percent of Americans will develop type 2 diabetes in their lifetime. The risk is highest among people of color: According to the CDC report, at least half of Black and Hispanic children will go on to develop diabetes by adulthood. The increase in type 2 diabetes is attributed to the startling rise in obesity rates. Currently, nearly 30 percent of adults in the U.S. are obese — a new record high — and another 35 percent are overweight.
Preventing and managing gestational diabetes
Because of the significant health risks associated with gestational diabetes, it is important to start treatment for the condition as quickly as possible.
The goal of treatment for gestational diabetes aims to keep blood glucose levels equal to those of pregnant women who don’t have gestational diabetes. Treatment always includes special meal plans and scheduled physical activity; it may also include daily blood glucose testing and insulin injections. Physical activity and diet are considered particularly important components of treatment, as they lower the risk of obesity and future type 2 diabetes in the mother while also reducing the negative health effects of weight-related conditions on fetal development. General guidelines for exercise and nutrition among women with gestational diabetes include:
Exercising is safe for the vast majority of pregnancies, and for women with gestational diabetes, it can reduce the risk of complications.
- Eating a balanced diet. After you find out that you have gestational diabetes, you will meet with a registered dietitian to create a healthy eating plan. You will learn how to limit the amount of carbohydrate you eat as a way to control your blood sugar. You may also be asked to write down everything you eat and to keep track of your weight. In general, it is not a good idea to diet while you are pregnant. Most doctors recommend that women gain 25 lb (11.3 kg) to 35 lb (15.9 kg) during pregnancy. But if you are overweight or obese, your doctor may recommend that you eat less and gain less weight than other pregnant women. Overweight or obese women have a higher risk for high blood pressure and a blood circulation problem called preeclampsia.
- Getting regular exercise. Try to do at least 2½ hours a week of moderate exercise. One way to do this is to be active 30 minutes a day, at least 5 days a week. It’s fine to be active in blocks of 10 minutes or more throughout your day and week. Regular, moderate exercise during pregnancy helps your body use insulin better and helps control your blood sugar level. If you have never exercised regularly or were not exercising before you became pregnant, talk with your doctor before you start exercising. Low-impact activities, such as walking or swimming, are especially good for pregnant women. You may also want to try special exercise classes for pregnant women.
For those who do need to monitor their blood sugar, the American Diabetes Association suggests the following targets for women who develop gestational diabetes during pregnancy (more or less stringent glycemic goals may be appropriate for each individual):
- Before a meal (preprandial): 95 mg/dl or less
- 1-hour after a meal (postprandial): 140 mg/dl or less
- 2-hours after a meal (postprandial): 120 mg/dl or less
Women with gestational diabetes should also have regular follow-ups with their health care provider so that treatment can be changed as needed. Sticking with recommended treatment strategies for gestational diabetes significantly reduces the risk of pregnancy complications and may help avoid future health problems, as well.