NEW YORK (Reuters Health) – Treatment of mild gestational diabetes mellitus (GDM) cut the risks of fetal overgrowth, shoulder dystocia, cesarean delivery, and hypertensive disorders in a study reported in The New England Journal of Medicine for October 1.

By contrast, treatment of mild GDM did not significantly affect the primary outcome, a composite of stillbirth, perinatal death, and several neonatal complications, such as hyperbilirubinemia and hypoglycemia.

“While US obstetricians have pretty much blanketly accepted GDM as a worthy diagnosis, many do not consider milder cases as being all that significant. Thus, our study, which is the first large scale treatment trial for mild GDM, is important,” lead author Dr. Mark B. Landon, from Ohio State University, Columbus, told Reuters Health.

Dr. Landon and his colleagues studied 958 women, in the 24th to 31st week of pregnancy, with mild GDM, defined as an abnormal result on oral glucose tolerance testing, but with a fasting glucose level below 95 mg/dL. The subjects were randomized to receive usual prenatal care or GDM therapy, which included dietary intervention, self-monitoring of blood glucose, and insulin treatment if needed.

Rates of the primary outcome in the intervention group and in controls were similar: 32.4% vs. 37.0%. No perinatal deaths occurred in either group.

The intervention was, however, associated with significant reductions in mean birth weight (3302 vs. 3408 g), neonatal fat mass (427 vs. 464 g), the rate of large-for-gestational-age infants (7.1% vs. 14.5%), birth weight greater than 4000 g (5.9% vs. 14.3%), shoulder dystocia (1.5% vs. 4.0%), and cesarean delivery (26.9% vs. 33.8%).

The combined endpoint of preeclampsia and gestational hypertension also occurred less frequently in the intervention group: 8.6% vs. 13.6%.

“For over twenty years, like others, I have treated many women for mild GDM often wondering if diet intervention and self blood glucose monitoring affected their pregnancy outcomes,” Dr. Landon said. “Frankly, I was somewhat surprised that treatment carried with it both significant fetal and maternal benefits.”

In light of the study findings, he emphasized, “obstetricians should not dismiss mild cases of GDM as being insignificant since aggressive intervention does carry meaningful clinical benefit.”

In an accompanying editorial, Dr. David A. Sacks, from Kaiser Foundation Hospital, Bellflower, California, comments that “although further research is needed, a focus on monitoring and minimizing excessive weight gain during pregnancy for all women seems to be a prudent and inexpensive policy, the benefits of which, for both mother and baby, may extend far beyond birth.”

Reference:
N Engl J Med 2009;361:1339-1348,1396-1398.