Prevention key for reducing risk of gestational, Type 2 diabetes

Here’s some good news for women who have, or have had, gestational diabetes: moderate exercise—as little as a 30 minutes of walking each day, 5 days a week—may reduce the risk of developing Type 2 diabetes later in life.

This encouraging finding comes out of the Diabetes and Women’s Health Study, from Dr. Cuilin Zhang and her colleagues in NICHD’s Division of Intramural Population Health Research. The Study seeks to determine the risk for Type 2 diabetes among women who have had gestational diabetes—high blood sugar during pregnancy in a woman who didn’t have high blood sugar previously.

Women who have gestational diabetes—and their children—are at higher risk for Type 2 diabetes later in life. In fact, having gestational diabetes increases a woman’s risk of developing Type 2 diabetes within 10 to 20 years after pregnancy by 35 to 60 percent. Gestational diabetes also increases the risks for other pregnancy complications, such as preeclampsia (a spike in blood pressure that can lead to seizures and death) or the need for a cesarean delivery because of a larger-than-normal baby.

If not controlled, Type 2 diabetes can lead to such serious consequences as heart attack, stroke, neurological problems, and kidney damage. Long-term injury to blood vessels can result in the need to amputate toes, feet, or entire limbs.

Dr. Zhang’s work shows that, with both gestational diabetes and Type 2 diabetes, prevention can go a long way toward reducing future risk. A healthy diet, maintaining a healthy weight, and exercise—both before and after pregnancy—is associated with greatly reduced risk.

In the most recent of their studies, Dr. Zhang and her colleagues found that the more women exercised after pregnancy, the less likely they were to develop Type 2 diabetes. Indeed, even moderate physical activity—30 minutes of walking, 5 days a week—cut risk for Type 2 diabetes by 47 percent. This study is the first to link exercise alone to reduced risk of Type 2 diabetes. Earlier research, sponsored by our sister NIH institute, the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), also linked exercise with reduced risk of Type 2 diabetes in women with gestational diabetes. In that study, however, exercise was combined with a healthy diet and weight loss and was not studied as a separate factor.

Of course, women who have had gestational diabetes can also take other steps to reduce the chances of Type 2 diabetes. In a 2012 study, Dr. Zhang and her colleagues reported that following a healthy diet in the years after pregnancy also was associated with decreased Type 2 diabetes risk. The greatest reductions in risk were seen among women whose diets were rich in whole grains, fresh fruits, vegetables, and legumes and included some poultry, seafood, and nuts but only limited amounts of red meat and processed meat. For these women, the risk of Type 2 diabetes was reduced by about 50 percent.

In still earlier work, the NICHD research team found that such healthy practices were beneficial before pregnancy. A low carbohydrate diet, largely from vegetable food sources (with limited animal foods), significantly reduced gestational diabetes risk. And, as with preventing Type 2 diabetes after gestational diabetes, the NICHD scientists also found that vigorous exercise before pregnancy reduced the chance of gestational diabetes.

Conversely, unhealthy habits increased gestational diabetes risk:

• A diet low in fiber, and with a high glycemic index (a measure of how rapidly carbohydrates in food are converted to blood sugar), before pregnancy substantially increased the risk for gestational diabetes.
• Women who, before pregnancy, regularly drank sweetened cola—high in added sugar—were at greatly increased risk for gestational diabetes. Sweeteners—like table sugar and high fructose corn syrup—added during food processing and preparation, or at the table, also have a high glycemic index.
• Also linked to increased gestational diabetes risk were pre-pregnancy diets high in animal fat and cholesterol and high in red and processed meat.

Although maintaining a healthy weight can greatly reduce risk for gestational diabetes, women who are at a healthy weight may still develop the condition. For this reason, U.S. women are routinely tested for gestational diabetes between weeks 24 and 28 of pregnancy. Women who have two or more risk factors (PDF - 187 KB), such as being related to someone who has diabetes and being overweight, should be tested as soon as the pregnancy is confirmed.

It’s important to remember that gestational diabetes is treatable, and a woman and her health care provider can work together to create the best treatment plan. That plan often involves eating a healthy diet, as outlined above and approved by a health care provider, checking blood glucose levels, and moderate physical activity, such as walking, a prenatal aerobics class, or swimming. A woman with gestational diabetes may also be advised to take insulin or other medications.

For most women, blood glucose levels normalize after the baby is born. However, as we’ve learned from Dr. Zhang’s comprehensive body of research, prevention is key. Not only can a healthy diet and regular exercise reduce the risk for later Type 2 diabetes, they also help in preparing for later pregnancies.

Information on weight management and calories is available from the United States Department of Agriculture’s nutrition information Web site, ChooseMyPlate.gov. This site also includes a section on the role of physical activity in maintaining a healthy weight, and helpful information for pregnant and breastfeeding women.

Addendum

According to the 2013 America’s Children report, 25 percent of 12th grade students had used illicit drugs in the previous 30 days. Currently, many states are considering decriminalizing or even legalizing the use of marijuana. Although no one would advocate making the drug available to minors, it is likely that adolescents will have easier access to marijuana in the years to come. We have evidence that exposure to tobacco, alcohol, marijuana and other illicit drugs can affect the adolescent brain, but we lack evidence on their long term effects. The NICHD has joined with other NIH institutes in calling for a long term study that would begin following young children from early childhood—before they start using drugs— through to adulthood, to understand the effects of these substances on the brains and lives of young Americans. A detailed description of this proposal is available at the blog of Dr. Nora Volkow, the Director of the National Institute on Drug Abuse.

Originally posted: June 26, 2014