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Lower versus Higher Glycemic Criteria for Diagnosis of Gestational Diabetes

List of authors.
  • Caroline A. Crowther, M.D.,
  • Deborah Samuel, B.Ed.,
  • Lesley M.E. McCowan, M.D.,
  • Richard Edlin, Ph.D.,
  • Thach Tran, Ph.D.,
  • and Christopher J. McKinlay, Ph.D.
  • for the GEMS Trial Group*



Treatment of gestational diabetes improves maternal and infant health, although diagnostic criteria remain unclear.


Download a PDF of the Research Summary.

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 criterion was a fasting plasma glucose level of at least 92 mg per deciliter (≥5.1 mmol per liter), a 1-hour level of at least 180 mg per deciliter (≥10.0 mmol per liter), or a 2-hour level of at least 153 mg per deciliter (≥8.5 mmol per liter). The higher glycemic criterion was a fasting plasma glucose level of at least 99 mg per deciliter (≥5.5 mmol per liter) or a 2-hour level of at least 162 mg per deciliter (≥9.0 mmol per liter). The primary 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). Secondary outcomes were maternal and infant health.


A total of 4061 women underwent randomization. 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. Among 2019 infants born to women in the lower-glycemic-criteria group, 178 (8.8%) were large for gestational age, and among 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 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.


The use of lower glycemic criteria for the diagnosis of gestational diabetes did not result in a lower risk of a large-for-gestational-age infant than the use of higher glycemic criteria. (Funded by the Health Research Council of New Zealand and others; GEMS Australian New Zealand Clinical Trials Registry number, ACTRN12615000290594.)

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Lower Glycemic Criteria for Gestational Diabetes Diagnosis

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Funding and Disclosures

Supported by a 3-year project grant (ID14/104) from the Health Research Council of New Zealand, and grants from Counties Manukau Health Tupu Fund, the Liggins Institute Philanthropic Fund, and the New Zealand Society for the Study of Diabetes.

Disclosure forms provided by the authors are available with the full text of this article at

A data sharing statement provided by the authors is available with the full text of this article at

We thank all the women and infants who participated in this trial, the midwives and medical staff who counseled eligible women, and the staff who conducted the trial at each of the sites.

Author Affiliations

From the Liggins Institute (C.A.C., D.S., C.J.M.), the Department of Obstetrics and Gynaecology (L.M.E.M.), and the School of Population Health (R.E.), University of Auckland, Auckland, New Zealand; and Osteoporosis and Bone Biology, Garvan Institute of Medical Research, Sydney (T.T.).

Dr. Crowther can be contacted at or at the Liggins Institute, University of Auckland, Bldg. 503, Level 2, 85 Park Rd., Auckland 1142, New Zealand.

The members of the GEMS Trial Group are listed in the Supplementary Appendix, available at

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