Study Favors Treating Gestational Diabetes

By Robert Shmerling, M.D.
Content provided by the Faculty of the Harvard Medical School

Treating even mild gestational diabetes can help the mother and baby, a study has found. This form of diabetes occurs during pregnancy. Usually it goes away afterward. The study looked at 958 women with mild cases of the condition. They were randomly assigned to receive treatment or not. Treatment included advice on diet to help control blood sugar. A small number of women needed insulin, too. The treated women gained an average of 5 pounds less than the others. They were only half as likely to have babies larger than 9 pounds. Fewer of them needed a cesarean section. They also were less likely to develop pre-eclampsia, a dangerous condition. The study appeared in the New England Journal of Medicine. The Associated Press wrote about it October 1.

What Is the Doctor's Reaction?

It's common to hear news about remarkably small babies born early. But you don't hear nearly as much about remarkably large babies.

Last week, a woman in Indonesia gave birth to a baby that weighed 19.2 pounds. That's more than twice the size of an average newborn. However, he did not break the world record of 23 pounds. That was set more than 100 years ago.

What you may have missed in the news about this large baby was that his mother had diabetes. Why does this matter? It's long been known that women with diabetes tend to deliver larger babies. Large babies are often healthy. But the larger the baby, the higher the rate of problems during delivery. These include nerve injuries and fractures. There are also risks to the mother when the baby is unusually large. These include higher rates of cesarean section and high blood pressure.

Diabetes that develops during pregnancy is called gestational diabetes. Treatment can reduce the likelihood of having an abnormally large baby. But, in some women blood sugar is only slightly high. For them, the benefits of treatment are uncertain. A new study aims to clarify whether mild gestational diabetes should be treated.

Researchers published their results in the New England Journal of Medicine. The study enrolled 958 women with mild gestational diabetes. They were randomly assigned into two groups. One group received treatment for gestational diabetes and the other did not.

The results showed that treatment helped. Women in the treatment group were significantly less likely to:

  • Require a cesarean section

  • Deliver a large baby

  • Have a problem during delivery in which the baby's shoulder becomes stuck in the mother's pelvis

  • Develop high blood pressure or pre-eclampsia – Pre-eclampsia is a serious health problem that develops during some pregnancies. Signs include sudden high blood pressure, fluid retention, protein in the urine and sometimes seizures.

It's important to have strong evidence to support the treatment of gestational diabetes. Without evidence, we don't know whether treatment might cause more harm than good. These findings should make treatment of mild gestational diabetes even more common than it already is. And that could reduce problems the condition causes. It may even improve the long-term health of infants born to women with gestational diabetes.

What Changes Can I Make Now?

You can't rely on symptoms to know if you have gestational diabetes. Most women with this condition have no symptoms. If you are pregnant, talk to your obstetrician about routine screening tests. The tests include a series of blood sugar measurements before and after you drink a sugary beverage.

If your results reveal high blood sugar levels, don't ignore them. As shown in this new study, even slightly high levels should prompt treatment. This includes dietary changes, control of weight gain and, if necessary, insulin treatment. Obesity or too much weight gain during pregnancy can increase your risk of developing gestational diabetes. Advice about weight gain has varied over the years. But experts now suggest that the ideal amount of weight gain during pregnancy is 25 to 35 pounds. Less weight gain is recommended if you're overweight or obese before pregnancy.

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