New Zealand: The use of lower glycemic criteria compared to higher glycemic criteria for gestational diabetes diagnosis did not reduce the risk of large-for-gestational-age infants, according to results from the GEMS trial. The study was published in the New England Journal of Medicine on August 18, 2022.
It is known that gestational diabetes treatment betters maternal and infant health but there is no clarity on its diagnostic criteria. To fill this knowledge gap, Caroline A. Crowther, Liggins Institute, University of Auckland, Auckland, New Zealand, and colleagues conducted the study with an aim to improve the benefits of screening for gestational diabetes and minimize potential harms.

The study included women at 24 to 32 weeks gestation. They were randomly assigned in the ratio of 1:1 to be evaluated for gestational diabetes with the use of lower or higher glycemic criteria for diagnosis.
The lower glycemic criterion was a fasting plasma glucose level of at least 92 mg per deciliter, a 1-hour level of at least 180 mg per deciliter, or a 2-hour level of at least 153 mg per deciliter. The higher glycemic criterion was a fasting plasma glucose level of at least 99 mg per deciliter or a 2-hour level of at least 162 mg per deciliter.
The main outcome was the birth of an infant who was large for gestational age -- defined as a birth weight above the 90th percentile according to Fenton–World Health Organization standards. Maternal and infant health were the secondary outcomes. A total of 4061 women underwent randomization.
Gestational diabetes diagnosis was made in 310 of 2022 women (15.3%) in the lower-glycemic-criteria group and in 124 of 2039 women (6.1%) in the higher-glycemic-criteria group.
Among 2019 infants born to women in the lower-glycemic-criteria group, 8.8% were large for gestational age, and among 2031 infants born to women in the higher-glycemic-criteria group, 8.9% were large for gestational age.
Induction of labor, use of health services, use of pharmacologic agents, and neonatal hypoglycemia were more common in the lower-glycemic-criteria group than in the higher-glycemic-criteria group.
The results for the other secondary outcomes were similar in the two trial groups, and there were no substantial between-group differences in adverse events.
Among the women in both groups who had glucose test results that fell between the lower and higher glycemic criteria, those who were treated for gestational diabetes (195 women), as compared with those who were not (178 women), had maternal and infant health benefits, including fewer large-for-gestational-age infants.
"Lower glycemic criteria for gestational diabetes diagnosis did not result in a lower risk of a large-for-gestational-age infant than higher glycemic criteria use," the researchers concluded.
Reference:
New England Journal of Medicine. Source Reference: Crowther CA, et al "Lower versus higher glycemic criteria for diagnosis of gestational diabetes" N Engl J Med 2022; DOI: 10.1056/NEJMoa2204091.