Gestational diabetes guidelines in a HAPO world.

The impact of gestational diabetes on maternal and fetal health has been increasingly recognized. However, universal consensus on the diagnostic methods and thresholds has long been lacking. Published guidelines from major societies differ considerably from one another, ranging in recommendations from aggressive screening to no routine screening at all. As a result, real-world practice is equally varied. The recently published Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study, and two randomized controlled trials evaluating treatment of mild maternal hyperglycemia, have served to confirm the findings of smaller, nonrandomized studies solidifying the link between maternal hyperglycemia and adverse perinatal outcomes. In response to these studies, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) has formulated new guidelines for screening and diagnosis of diabetes in pregnancy. Key components of the IADPSG guidelines include the recommendation to screen high-risk women at the first encounter for pre-gestational diabetes, to screen universally at 24-28 weeks' gestation, and to screen with use of the 75-g oral glucose tolerance test interpreting abnormal fasting, 1-h, and 2-h plasma glucose concentrations as individually sufficient for the diagnosis of gestational diabetes. Furthermore, to translate the continuous association between maternal glucose and adverse outcomes demonstrated in the HAPO cohort, they recommend thresholds for positive screening tests at which the odds of elevated birth weight, cord C-peptide, and fetal percent body fat are 1.75 relative to odds of those outcomes at mean glucose values. Opponents to the IADPSG recommendations will likely be those who favor risk-based screening in addition to those who endorse the 50-g glucose challenge test followed by the 100-g oral glucose tolerance test as a more cost-effective, familiar, and possibly, well-validated screening tool. Others may argue that the diagnostic thresholds chosen by the IADPSG are arbitrary and will continue to miss many cases of abnormal glucose metabolism and therefore leave open the possibility of adverse perinatal outcomes due to untreated gestational diabetes. Finally, the potential economic impact of the IADPSG guidelines are unknown, and with minimal long-term data yet available on the offspring of the HAPO cohort, a true cost-effectiveness analysis will be difficult to perform accurately. Given these potential points of contention, the responses of professional and international groups to the IADPSG guidelines are difficult to gauge. Regardless, these guidelines serve to advance the discussion on appropriate screening and diagnosis of diabetes in pregnancy. 2010. Published by Elsevier Ltd.