Treating mild gestational diabetes lowered the risks of fetal overgrowth, shoulder dystocia, cesarean delivery, and gestational hypertension, as well as decreasing maternal weight gain, based on a study of almost 1,000 women.
However, treating mild gestational diabetes did not improve the composite primary outcome of neonatal mortality, hypoglycemia, hyperbilirubinemia, hyperinsulinemia, and birth trauma in a multicenter, randomized clinical trial designed to establish whether such treatment reduced perinatal and obstetric complications.
“The findings from our trial confirm a modest benefit from the identification and treatment of women with mild carbohydrate intolerance during pregnancy,” said Dr. Mark B. Landon and his associates in the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.
The investigators assessed 958 women who had mild gestational diabetes—defined as a fasting glucose level of less than 95 mg/dL plus two to three timed glucose measurements that exceeded established thresholds—between 24 and 31 weeks' gestation. A total of 473 were randomly assigned to receive standard prenatal care and 485 to receive formal nutritional counseling, diet therapy, and insulin as needed (N. Engl. J. Med. 2009;361:1339–48).
The intervention group performed daily self-monitoring of fasting and postprandial blood glucose levels. The researchers verified compliance with glycemic monitoring and documented that target glucose thresholds were achieved.
There was no difference between the two groups in the primary composite outcome of neonatal death and complications known to be associated with maternal hyperglycemia. Individual rates of these complications (neonatal hypoglycemia, hyperbilirubinemia, birth trauma, and elevated cord-blood C-peptide levels) also did not differ significantly, Dr. Landon of Ohio State University, Columbus, and his colleagues said.
However, the intervention significantly reduced mean birth weight, neonatal fat mass, the rate of large-for-gestational-age infants, and the rate of infants weighing 4,000 g or more.
Cesarean delivery was significantly less frequent in the intervention group (27%) than in the control group (34%), as were shoulder dystocia, gestational hypertension, and preeclampsia.
Moreover, both maternal body mass index at delivery and maternal weight gain during pregnancy were lower in the intervention group than in controls.
“Increased birth weight and neonatal fat mass may have long-term health implications for the offspring of mothers with gestational diabetes mellitus, including an increased risk of impaired glucose tolerance and childhood obesity. Long-term follow-up studies are needed to determine whether treatment of gestational diabetes mellitus can reduce the risk of these complications,” Dr. Landon and his associates wrote.
In the meantime, these study findings “provide further compelling evidence that among women who have gestational diabetes mellitus and normal fasting glucose levels, treatment that includes dietary intervention and insulin therapy, as necessary, reduces rates of fetal overgrowth, cesarean delivery, and preeclampsia,” they said.
This study was supported by grants from the National Institute of Child Health and Human Development, the General Clinical Research Centers, and the National Center for Research Resources. No financial conflicts of interest were reported.