Impact of the International Association of Diabetes and Pregnancy Study Groups criteria for gestational diabetes.

Aims: To evaluate the diagnostic criteria of the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and alternative criteria in terms of resultant prevalence of gestational diabetes mellitus (GDM) and measures of diagnostic impact.

Methods: The Brazilian Gestational Diabetes Study (EBDG) is a cohort of pregnant women enrolled consecutively in prenatal care clinics of the Brazilian National Health Service from 1991 to 1995, a time and setting in which those with lesser than diabetes hyperglycemia rarely received drug treatment. Eligibility criteria were age ≥20 years, gestational age 20-28 weeks and no history of diabetes outside pregnancy. After interview and anthropometric measurements, a standardized 2h 75g OGTT was scheduled. Women were followed through early postpartum.

Results: Prevalence of GDM defined by IADPSG criteria was 18.0% (95% CI 16.9-19.0), ranging from 2.7 to 17.0% with the alternative criteria. Relative risks for large for gestational age (LGA) and preeclampsia were generally small. The diagnostic impact assessed by pre- to post-test gain in the probability of an outcome was also small (3.6% for LGA and 0.5% for preeclampsia). Alternative criteria reached maximum gains of 9.7% and 5.3%, respectively. The fractions of LGA births and preeclampsia attributable to GDM by the IADPSG criteria were small, 6.7% and 3.5%, respectively.

Conclusions: The IADPSG criteria identify more women as having GDM but their diagnostic and population impacts with respect to adverse outcomes are small. Alternative definitions, although also presenting small diagnostic and population impacts, showed advantages which may be useful in specific settings.