Pregnant women are routinely tested for gestational diabetes

On call


Since I have no history of diabetes, could you explain why my obstetrician measured my blood sugar after his nurse had me put some sugar in my mouth?

During the 24th to 28th weeks of pregnancy, the vast majority of obstetricians now order a test of the blood sugar (glucose) level one hour after oral administration of 50 grams of glucose. The test is carried out to detect the presence of gestational diabetes, which is defined as an abnormality of sugar metabolism that begins or is recognized during pregnancy.

In this country, gestational diabetes occurs in 2 to 5 percent of pregnancies. The risk is increased with obesity, older maternal age, a first-degree relative (parent, brother or sister) with diabetes and a history of either fetal macrosomia (an offspring with a birth weight greater than nine pounds) or gestational diabetes in a prior pregnancy. Gestational diabetes recurs in about 50 percent of women who had the problem in a previous pregnancy.

Left untreated, elevated blood glucose levels are associated with an increased risk of fetal death around the time of birth and off spring with macrosomia or low blood glucose levels. Initial management consists of reducing total calories and limiting carbohydrates to 40 percent of daily calories. Regular exercise may also help to control blood glucose. Insulin therapy is started if blood glucose levels remain elevated despite following these measures. Most studies have found no increase in fetal mortality when blood glucose levels are controlled in this way.

Less than 10 percent of women with gestational diabetes have evidence of diabetes or any abnormality of glucose metabolism six to eight weeks after delivery. In one study, however, nearly 40 percent of women with a history of gestational diabetes had developed diabetes within 20 years after their pregnancies. There also is some evidence that gestational diabetes is later associated with an increased risk of high blood pressure, high blood lipid levels and heart disease. The chance of developing these problems can be reduced by dietary measures and exercise to avoid the development of obesity.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.