Diabetes that strikes during pregnancy can lead to overweight fetuses and difficult deliveries. In the United States, most women who develop gestational diabetes, a temporary form of the disease, are told to limit caloric intake and to monitor their blood sugar. Some even get insulin shots. But not all doctors opt to treat the condition, citing inconsistent evidence that the measures make any difference.
Caroline A. Crowther of the University of Adelaide in Australia and her colleagues now report that close monitoring of blood sugar, diet counseling, and insulin treatment as needed for women with gestational diabetes reduce the chance of birth complications. This approach also lessened risk of postpartum depression.
"This is the first piece of really solid evidence that treating gestational diabetes can make a difference," says diabetes specialist Caren G. Solomon of Brigham and Women's Hospital in Boston, who didn't participate in the trial.
For their study, the researchers identified 1,000 women with gestational diabetes between 1993 and 2003 at hospitals in Australia and Britain. Roughly half of the women got repeated blood sugar testing, counseling about diabetes, and advice on controlling their calorie intake. One-fifth of this treated group required—and received—insulin shots during pregnancy. The other women weren't told they had gestational diabetes and received only routine prenatal care.
The researchers justified this unusual step, which they acknowledge is controversial, by noting that there had been "no conclusive evidence regarding the effects of treatment of gestational diabetes."
The treated group had no stillbirths or newborn deaths, whereas among the untreated women, there were three stillbirths and two newborn deaths. The difference, however, may have been due to chance or unrelated factors.
Half as many babies born to treated mothers weighed in at more than 4 kilograms (about 8.8 pounds) as compared with babies born to the other group. Largely because of this, only 1 percent of the women getting the treatment experienced complications during delivery, compared with 4 percent of the other women, the researchers report in the June 16 New England Journal of Medicine.
Moreover, only half as many women in the treatment group reported being depressed 3 months after giving birth as did the women not told that they had gestational diabetes.
The strongest finding of the study is that intensive monitoring and treatment of gestational diabetes results in fewer overweight babies, comments obstetrician Mark B. Landon of the Ohio State University College of Medicine in Columbus.
Gestational diabetes, typically appearing in the second or third trimester, afflicts 3 to 7 percent of pregnancies, Solomon says. When a pregnant woman develops diabetes, her cells don't take up glucose readily, so her blood concentrations of the sugar rise. Because glucose passes through the placenta, the fetal blood also becomes rich in the sugar, causing weight gain.
Besides increasing the likelihood of birth complications, Landon says, an abundance of sugar forces the fetus to manufacture extra insulin. Even after the umbilical cord is cut during delivery, the baby continues this revved-up insulin production, driving down blood sugar concentrations, he explains.
The new work "will be very important in shaping future recommendations for screening and treatment," Solomon predicts.
Caroline A. Crowther
Department of Obstetrics and Gynecology
University of Adelaide
King William Road
North Adelaide, South Australia 5006
Mark B. Landon
Ohio State University
Department of Obstetrics and Gynecology
1643 Upham Drive
Columbus, OH 43210
Caren G. Solomon
Harvard Medical School
Brigham & Women's Hospital
Fish Center for Women's Health
815 Boylston Street, Ste. 402
Chestnut Hill, MA 02467
Garner, P., et al. 1997. A randomized controlled trial of strict glycemic control and tertiary level obstetric care versus routine obstetric care in the management of gestational diabetes: A pilot study. American Journal of Obstetrics and Gynecology 177(July):190-195. Abstract.
Greene, M.F., and C.G. Solomon. 2005. Gestational diabetes mellitus—time to treat. New England Journal of Medicine 352(June 16):2544-2546. Extract available at [Go to].
Landon, M.B., et al. 2002. A planned randomized clinical trial of treatment for mild gestational diabetes mellitus. Journal of Maternal-Fetal Neonatal Medicine 11(April):226-231. Abstract.
Langer, O., et al. 2005. Gestational diabetes: The consequences of not treating. American Journal of Obstetrics and Gynecology 192(April):989-997. Abstract available at [Go to].
Silverman, B., et al. 1995. Impaired glucose tolerance in adolescent offspring of diabetic mothers: Relationship to fetal hyperinsulinism. Diabetes Care 18(May):611-617. Abstract available at [Go to].