March 12, 2014
News Review From Harvard Medical School -- Gestational Diabetes May Increase Heart Risk
Gestational diabetes may increase the risk of heart disease, even for women who don't develop type 2 diabetes later. That's the conclusion of a new study that included nearly 900 women. They did not have heart disease or diabetes when the study began. About 13% developed gestational diabetes. This form of diabetes occurs during pregnancy. It usually goes away afterward. But it does increase the risk of developing type 2 diabetes. Diabetes increases the risk of heart disease. After 20 years of follow-up, researchers measured the women's carotid arteries. Thick arteries may indicate atherosclerosis, a buildup of deposits inside arteries. This condition can lead to heart disease or stroke. Carotid arteries were thicker in women who had gestational diabetes in the past than in other women. This was true even if they had not developed type 2 diabetes or metabolic syndrome since pregnancy. Metabolic syndrome is a group of health factors that increase the risk of heart and blood vessel disease. Arteries also were thicker for women who had gestational diabetes but were not obese before they got pregnant. The Journal of the American Heart Association published the study online March 12. HealthDay News wrote about it.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
If you've ever been pregnant, your doctor may have asked you to take a "glucose screening test" or "glucose tolerance test." You consume a sweet drink and then have your blood sugar checked after an hour or so. If your sugar is high, you may have the test repeated. For example, it may be checked one, two and three hours after the sugary drink.
Your doctor is checking for a condition called gestational diabetes mellitus. This form of diabetes develops during pregnancy. It often occurs in women without a history of diabetes.
These tests have been performed for decades. They are recommended for several reasons:
- Knowing that a woman has gestational diabetes can help her doctors watch for problems during pregnancy. For example, the baby may be very large. This makes it more likely that a cesarean section will be necessary. There is also an increased risk of high blood pressure and other serious problems for the pregnant woman.
- Gestational diabetes increases a woman's lifetime risk of developing diabetes by up to seven times. It also increases the risk of developing metabolic syndrome. This is a combination of conditions, including at least three of the following:
- A large waistline
- High triglycerides (a type of blood fat) in the blood
- Low HDL cholesterol ("good cholesterol")
- High blood pressure
- High fasting blood sugar
Diabetes and metabolic syndrome, in turn, raise the risk of heart and blood vessel (cardiovascular) disease.
- In some women, diabetes may be discovered during pregnancy and persist after delivery.
So knowing a woman has gestational diabetes can have a profound impact on her medical care during pregnancy and in the future. When properly treated, most women with gestational diabetes deliver healthy babies.
Despite all that is known about gestational diabetes, some things are still not clear. For example, doctors have not known whether a woman with gestational diabetes who doesn't develop diabetes or metabolic syndrome after delivery has an increased risk of heart problems in the future. That's the subject of a newly published study.
The study included nearly 900 women who did not have diabetes or heart disease before pregnancy. About 13% of them developed gestational diabetes. Twenty years after delivery, each woman had an ultrasound of the carotid artery (a large artery in the neck) to measure its thickness. This is a measure of atherosclerosis, or hardening of the arteries, which is linked with heart attacks and strokes.
Here's what the researchers found out:
- There was more thickening of the carotid arteries in the women who developed gestational diabetes than in those who did not.
- This was true even among women with gestational diabetes who did not develop diabetes or metabolic syndrome after delivery.
- Similar findings were also noted for women who were not obese before pregnancy. This is important because obesity increases the risk of diabetes during and after pregnancy.
These findings suggest that gestational diabetes may matter more than we thought. Of course, it affects pregnancy and a woman's future risk of diabetes. Now it appears that it may also increase the risk of heart disease even in women who don't have a high risk for other reasons. And that could change what doctors do when gestational diabetes is diagnosed.
What Changes Can I Make Now?
Heart disease is the No. 1 cause of death for American women and men. So it's worth trying to reduce your risk. You can take these steps:
- Don't smoke.
- Exercise regularly.
- Avoid excess weight.
- Choose a healthy diet.
- Maintain a normal blood pressure.
- Keep your blood lipids (including cholesterol) in a good range.
- Get treatment for conditions that increase your risk of heart and blood vessel disease. These include diabetes, high cholesterol and high blood pressure.
If you have had gestational diabetes, this new research suggests that you have a higher risk of future heart and blood vessel disease. For you, the preventive measures above are particularly important. Whether other preventive measures are effective is unclear. These include taking aspirin or other "heart-protective" medicines.
You may be able to reduce your chances of having gestational diabetes in future pregnancies. An important step would be to lose excess weight before you become pregnant again.
What Can I Expect Looking to the Future?
This study provides new insights into the effects of gestational diabetes. However, it does not tell us what we can do about it. Future research will be needed to find effective ways to help women with gestational diabetes. I hope we also will find new and effective ways to prevent this condition from developing in the first place.