Treatment of gestational diabetes improves maternal and child health, although diagnostic criteria remain unclear.
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We randomly assigned women at 24 to 32 weeks gestation in a 1:1 ratio to be evaluated for gestational diabetes with the use of lower or higher glycemic criteria for diagnosis. The lower glycemic endpoint was a fasting blood glucose of at least 92 mg per deciliter (≥ 5.1 mmol per liter), a 1-hour blood glucose level of at least 180 mg per deciliter (≥ 10.0 mmol per liter), or a 2-hour blood glucose level. level of at least 153 mg per deciliter (≥8.5 mmol per liter). The highest glycemic endpoint was a fasting blood glucose of at least 99 mg per deciliter (≥ 5.5 mmol per liter) or a 2-hour blood glucose level of at least 162 mg per deciliter (≥ 9.0 mmol per liter ). The primary outcome was the birth of a large-for-gestational-age child (defined as a birth weight above the 90th percentile by Fenton and World Health Organization standards). Secondary outcomes were maternal and infant health.
A total of 4061 women were randomized. Gestational diabetes was diagnosed 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. Of the 2019 infants born to women in the lower glycemic criteria group, 178 (8.8%) were large for gestational age, and of the 2031 infants born to women in the higher glycemic criteria group, 181 (8.9 %) were large for gestational age (adjusted relative risk, 0.98; 95% confidence interval, 0.80 to 1.19; P = 0.82). Induction of labor, use of health services, use of pharmacological 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 differences between the groups with respect to adverse events. Among women in both groups whose blood glucose test results fell between the lower and upper glycemic criteria, those who were being treated for gestational diabetes (195 women), versus those who were not (178 women) , had maternal and child health benefits, including fewer large-for-gestational-age infants.
Using lower glycemic criteria for the diagnosis of gestational diabetes did not result in a lower risk of a large-for-gestational-age infant than using higher glycemic criteria. (Funded by the Health Research Council of New Zealand and others; Australian New Zealand GEMS Clinical Trials Registry Number, ACTRN12615000290594.)