Screening and treatment for gestational diabetes are currently recommended at 24-28 weeks’ gestation, with earlier testing recommended for women at increased risk, but the potential benefits of earlier intervention remain debatable, wrote David Simmons, MD, of Western Sydney University, Campbelltown, Australia, and colleagues.
“Until now, there has been complete equipoise over whether to treat hyperglycemia below that of overt diabetes early in pregnancy,” Dr. Simmons said in an interview. The conflicting questions: “Would early treatment reduce the excess deposition of fat on the baby with all of its sequelae; but would early treatment reduce fuel supply to some babies at a critical time and lead to SGA [small for gestational age]?” Dr. Simmons noted.
In a study published in the New England Journal of Medicine, Dr. Simmons and colleagues randomized 406 women aged 18 years and older with singleton pregnancies to immediate treatment for gestational diabetes. Another 396 women were randomized to a control group for deferred treatment or no treatment, based on results of an oral glucose tolerance test at 24-28 weeks’ gestation. All participants had at least one risk factor for hyperglycemia, and met the World Health Organization criteria for gestational diabetes. Women with preexisting diabetes or contraindicating comorbid medical conditions were excluded.
The study had three primary outcomes. The first was a composite of neonatal outcomes including birth before 37 weeks’ gestation, birth weight of 4,500 g or higher, birth trauma, neonatal respiratory distress, phototherapy, stillbirth or neonatal death, or shoulder dystocia.
The final sample included 748 women for adverse neonatal outcomes, 750 for pregnancy-related hypertension, and 492 for neonatal lean body mass. The mean age of the participants was 32 years; approximately one-third were white European and another third were South Asian. Overall baseline demographics were similar between the groups, and the initial oral glucose tolerance tests were performed at a mean of 15.6 weeks’ gestation.
Overall, 24.9% of women in the early treatment group experienced an adverse neonatal event vs. 30.5% of controls, for an adjusted risk difference of –5.6% and adjusted relative risk of 0.82.
Notably, in an exploratory subgroup analysis, respiratory distress occurred in 9.8% of infants born to women in the immediate treatment group vs. 17.0% of infants in the control group. “Neonatal respiratory distress was the main driver of the between-group difference observed for the first primary outcome,” the researchers wrote. A prespecified subgroup analysis suggested that the impact of an earlier intervention on adverse neonatal outcomes might be greater among women with a higher glycemic value and those whose oral glucose tolerance tests occurred at less than 14 weeks’ gestation, they noted. Stillbirths or neonatal deaths were similar and infrequent in both groups.
Pregnancy-related hypertension occurred in 10.6% of the immediate-treatment group and 9.9% of the controls group (adjusted risk difference, 0.7%). For the third outcome, the mean neonatal lean body mass was 2.86 g in the immediate-treatment group and 2.91 g for the controls (adjusted mean difference, −0.04 g).
No differences in serious adverse events related to either screening or treatment were noted between the groups.