Did you know that the higher-than-normal blood sugar associated with diabetes affects one in every 15 to 20 pregnancies? Thomas Buchanan, professor of medicine, says doctors can ask questions and perform exams to catch those women most likely to have gestational diabetes, without being too aggressive and performing unnecessary tests.

On an expectant mother's first doctor's visit, her physician should assess her for characteristics that place her at higher risk for gestational diabetes (such as obesity, diabetes in a close relative, a history of glucose intolerance and similar factors). High-risk women should get an oral glucose test early in the pregnancy to detect diabetes, and if they show no diabetes mellitus at that time, they should get another follow-up blood sugar test between the 24th and 28th week of pregnancy.

Women considered at low risk (under age 25, low-risk ethnic group, no close relatives with diabetes, no abnormal blood sugar levels in the past) don't need blood glucose testing for gestational diabetes. Women who don't fit either the high- risk or the low-risk profile can skip an oral glucose test during their first doctor's visit. However, they should have the test between the 24th and 28th week of pregnancy, when most cases of gestational diabetes occur.

Gestational diabetes has a relatively small impact on the health of the mother during pregnancy. The most common problems are high blood pressure--such as preeclampsia--so doctors should carefully monitor women's blood pressure, weight gain and hypertensive problems.

The more common problems caused by gestational diabetes during pregnancy affect the fetus. Basically, the extra glucose in the mother's bloodstream crosses the placenta to the baby, causing a subset of infants to become fat. Because of their size, these babies have problems during labor and delivery. They may suffer birth trauma such as fracture of the collarbone or nerve damage or they may have to be delivered by cesarean section. Treatment during pregnancy is designed to prevent these complications.

The cornerstone of that treatment is good nutrition so that a mother gets enough calories, but doesnpt see her blood sugar levels rise too high. Strategies include limiting carbohydrates to 40 percent of her calories, eating carbohydrates that do not boost blood sugar too much, and limiting calorie intake for overweight women.

Once good nutrition is in place, women can either learn to check their own blood sugars at home or visit their doctor every one to two weeks for a fasting blood sugar test, Buchanan said. They should also have an ultrasound to check the baby's growth somewhere around the 30th week of pregnancy. If the mother's blood sugar levels are too high or the baby shows signs of growing too fat, then insulin treatment might be needed to prevent complications at birth.

The researchers suggest that doctors watch the health of the children of diabetic mothers as the children grow up, regularly monitoring height, weight and diet, while promoting exercise to avoid obesity.

Although women who get diabetes during pregnancy often see it go away after birth, these women are at risk of developing the common adult form of diabetes within five to sixteen years of their pregnancy.

Research done at USC suggests that diabetes develops because the tissues of the body do not respond well to insulin, the hormone that normally controls blood sugar levels. As a result, the beta cells in the pancreas have to work overtime to made extra insulin and they wear out, leading to diabetes. So, physicians treating women with a history of gestational diabetes should recommend tools to reduce the resistance to insulin, such as exercise, maintaining a normal weight and avoiding certain drugs.

Doctors should also be sure patients have their blood sugar checked at least annually, Buchanan said. Finally, they should encourage patients to participate in family planning so that they can be sure their blood sugar levels are in the safe range before they ever become pregnant, to optimize the health of their next baby.