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Using a lower threshold for diagnosing gestational diabetes in mothers didn't reduce the risk of large-for-gestational-age infants, according to the GEMS trial.

After randomizing over 4,000 pregnant women, 15.3% were diagnosed with gestational diabetes using lower, and commonly recommended, glycemic criteria versus 6.1% using a higher threshold, Caroline Crowther, MD, of the University of Auckland in New Zealand, and colleagues reported.

But the lower criteria had no impact on the proportion of infants born large for gestational age, at 8.8% in the lower-glycemic-criteria group versus 8.9% in the higher-glycemic-criteria group (adjusted relative risk 0.98, 95% CI 0.80-1.19, P=0.82), according to findings published in the .

Despite this, some differences were seen in regards to some secondary outcomes. For example, babies born to mothers in the lower-glycemic-criteria group had higher rates of neonatal hypoglycemia, induction of labor, use of health services, and use of pharmacologic agents.

"Most other outcomes were similar between the diagnostic groups, although babies born to mothers in the lower-criteria group were more likely to be treated for neonatal hypoglycemia," Crowther told 番茄社区 via email.

Mothers in the lower-criteria group "were more likely to have their labor induced, receive drug treatment for diabetes, and use more health services," she added.

"Women with milder gestational diabetes who were treated or not depending on whether they were allocated to the lower or higher criteria did however show important differences," said Crowther. "Pre-eclampsia, birth of a large for gestational age infant and shoulder dystocia were less likely in women diagnosed and treated with milder gestational diabetes, compared to women with milder gestational diabetes not diagnosed and therefore not treated."

Several other outcomes -- birth weight, length, head circumference, small-for-gestational-age, macrosomia, and adverse events -- were not different between the groups.

All women underwent a 75-g oral glucose-tolerance test between 24 to 32 weeks' gestation, and criteria for diagnosing gestational diabetes in the two groups were as follows:

• Lower: fasting plasma glucose level of ≥92 mg/dL, 1-hour level of ≥180 mg/dL, or a 2-hour level of ≥153 mg/dL
• Higher: fasting plasma glucose level of ≥99 mg/dL or a 2-hour level of ≥162 mg/dL

This lower threshold is in line with the one-step approach recommended by the International Association of the Diabetes and Pregnancy Study Groups, which the says may be the preferred approach.

"At the population level, use of the lower criteria compared with the higher criteria increased the proportion of women diagnosed with gestational diabetes, but did not reduce perinatal morbidity -- and use of health services was increased," Crowther pointed out. "However, for the women with milder gestational diabetes there were health benefits for them and their baby from detection and treatment."

In an , Michael Greene, MD, of Harvard Medical School in Boston, said the "perfect line for diagnosing gestational diabetes has yet to be drawn."

"Ultimately, diagnosing gestational diabetes in more women through the use of the lower glycemic criteria in this trial neither improved nor worsened outcomes for the mothers or their babies," wrote Greene.

GEMS randomized 4,061 women to either the lower- or higher-glycemic-criteria groups. The study's primary outcome, infants born large for gestational age, was defined as a birth weight over the 90th percentile.

At baseline, women in the study had an average age of 31-32 years, about half were having their first child, and their median body mass index was 26.5-26.6. For demographics, 40% were white, a third were Asian, 15-16% were Pacific Islander, and 5-6% were Maori.

A little more than a third of women in each arm had a family history of diabetes and 4% had chronic hypertension.

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