Oral Drug May Control Pregnancy-Related Diabetes

From the WebMD Archives

Oct. 18, 2000 -- Diabetes is the most common medical complication of pregnancy, occurring in 3% to 10% of all pregnancies. Some women who become diabetic during pregnancy need daily insulin injections, but a new study suggests that an oral drug called glyburide might free thousands of expectant mothers from the needle.

The study, published in The New England Journal of Medicine, reports that glyburide (marketed as DiaBeta, Micronase, or Glynase) can control so-called gestational diabetes. Further, study author Oded Langer, MD, noted no increase in birth defects in the babies of women who took glyburide while pregnant, compared with those born to women who took insulin. His study compared 201 women with pregnancy-related diabetes who took the oral drug with 203 who took insulin.

Gestational diabetes usually goes away after pregnancy. But if poorly controlled, it can affect the baby, leading to such difficulties at birth as large size (which can complicate delivery), low blood sugar, and breathing problems, and, later on, to an increased risk of obesity and diabetes, according to the American Diabetes Association. Some women are at particularly high risk for this type of diabetes. For example, the gestational diabetes rate is higher among Mexican-American and African-American women. Being overweight or older also increases the risk.

Most women who become diabetic during pregnancy try diet first to control their high blood sugar, but this doesn't always work. Doctors have rarely given other oral diabetes drugs to pregnant women because there has been concern about the drugs' possible effects on the baby before or shortly after birth.

But Langer reports that glyburide does not cross the placenta and so is unlikely to affect the fetus. He found that birth defects were rare in babies born to either group of women in his study, and that there was no difference in the rate of complications after delivery. Also, glyburide was less likely than insulin to "overdo" blood sugar control and cause the mother's blood sugar to go dangerously low. Langer is a professor and chair of obstetrics and gynecology at St. Luke's-Roosevelt Hospital Center in New York.


Lois Jovanovic, MD, who reviewed the study for WebMD, says that it must be viewed with some caution. Jovanovic, director and chief scientific officer of the Samsung Medical Research Institute in Santa Barbara, Calif., says she is not convinced the study was large enough to prove that glyburide is safe for the developing fetus.

Langer tells WebMD that fetal safety was the investigators' highest concern and that they tested glyburide because they had previously shown that it does not pass from mother to baby across the placenta. "We examined every type of fetal effect we found mentioned anywhere, and none occurred more often with glyburide than with insulin," Langer says.

But Langer tells WebMD that the key to having a healthy baby despite gestational diabetes is not which drug a woman takes. The important step, he says, is for the mother to carefully and repeatedly check her blood sugar level and adjust her medication accordingly. Women in this study checked their blood sugar seven times each day. Most problems, Langer says, are due to high sugar level in the mother's blood, which stimulates the fetus to produce too much insulin.

"Only if blood glucose is monitored closely and the proper tests are done throughout pregnancy can you have the healthiest baby," Langer says. "It would be a mistake for a mother to think that she can just take a few pills and take care of the problem."

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