SAN DIEGO — Treatment of mild gestational diabetes did not reduce the frequency of several commonly reported morbidities associated with diabetic pregnancy, results from a large multicenter randomized trial demonstrated.
However, treatment did lower birth weight and resulted in a 50% reduction in macrosomia, as well as lower neonatal fat mass, rates of shoulder dystocia, cesarean delivery, preeclampsia, and gestational hypertension.
“Identification and treatment of mild gestational diabetes is clearly associated with significant clinical benefits,” Dr. Mark B. Landon said at the annual meeting of the Society for Maternal-Fetal Medicine.
The incidence of gestational diabetes, defined as glucose intolerance with onset or first recognition during pregnancy, is rising in the United States, said Dr. Landon, professor of obstetrics and gynecology at Ohio State University, Columbus. More than 45 years ago, researchers “first proposed criteria for the diagnosis, which were based on the subsequent development of adult-onset diabetes and not on any association between carbohydrate intolerance and adverse pregnancy outcomes,” he said. “Thus, the clinical significance of gestational diabetes and, in particular, mild gestational diabetes as it relates to perinatal morbidity, is unclear and has been challenged for decades.”
Based largely on results of retrospective single-center studies to date, there has been “widespread acceptance of screening and treatment of gestational diabetes by professional organizations with little evidence of demonstrable benefit,” he said.
However, in 2003 and 2008, the U.S. Preventive Services Task Force concluded that there is insufficient evidence to determine if treatment of mild gestational diabetes provides a health benefit.
The controversy prompted the maternal-fetal medicine units network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development to conduct a randomized trial to determine if treatment of mild gestational diabetes reduced perinatal morbidity.
For the study, 958 women with a singleton gestation who met criteria for mild gestational diabetes (a fasting value of less than 95 mg/dL on a blinded 3-hour oral glucose tolerance test) were allocated to one of two groups. The 485 women in the treatment group received formal nutrition counseling, instruction on self-monitoring of blood glucose, and insulin administration, if necessary. The 473 controls received standard routine obstetric care, and clinicians and study participants were unaware of their glucose tolerance test results.
The primary end point was a composite outcome that consisted of perinatal mortality; neonatal hypoglycemia defined as a value less than 35 mg/dL during the first 2 hours of life without feeding; a serum bilirubin greater than 8 mg/dL between 16 and 36 hours of life, hyperinsulinemia as reflected by a cord blood C-peptide greater than the 95th percentile, or birth trauma.
The average age of the study participants was 29 years. There were no differences in the frequency of composite primary neonatal outcome (32% in the treatment group vs. 37% in the control group).
Among secondary outcomes, Dr. Landon and his associates observed a significant difference between the treatment and control groups in mean birth weight (3,302 g vs. 3,408 g, respectively), fetal fat mass (427 g vs. 464 g), and frequency of infants weighing greater than 4,000 g at birth (6% vs. 14%).
No differences were seen inNICU admission, preterm delivery, respiratory distress syndrome, or need for intravenous glucose treatment.
In maternal outcomes, induction of labor rates were similar between the two groups (about 27%), but the treatment group had significantly lower overall rates of cesarean delivery (27% vs. 34%) and rates of cesarean corrected for abnormal presentation and prior cesarean (13% vs. 20%).
The shoulder dystocia rate also was reduced with treatment (2% vs. 4%) as was the rate of preeclampsia and gestational hypertension as a composite (9% vs. 14%).
Dr. Landon disclosed no conflicts of interest related to the study.
The clinical significance of mild gestational diabetes 'is unclear and has been challenged for decades.' DR. LANDON