Gestational diabetes: overview of the new consensus screening strategy and diagnostic criteria

Gestational diabetes (GDM) is a frequent medical condition during pregnancy. GDM is associated with an increased risk of complications for both the mother and the baby during pregnancy and birth. Women with GDM also have an increased risk of developing type 2 diabetes later in life. Two large randomised intervention trials demonstrated improvement in perinatal outcomes in the group that received treatment of mild glucose intolerance during pregnancy. However, there is lack of international uniformity in the approach to ascertainment and diagnosis of GDM. The HAPO trial studied for the first time on a very large scale the relationship between glucose tolerance of the mother and the risk for complications for both mother and child. The 'International Association of Diabetes and Pregnancy Study Groups (IADPSG)' subsequently published a new consensus for a screening strategy and diagnosis of GDM which has now been adopted by the American Diabetes Association (ADA). This remains controversial as the American College of Obstetricians and Gynecologists (ACOG) advices to continue with the two-step screening strategy, while other associations have not yet reached a consensus. The discussion now focuses on two issues: an improved detection of pregestational diabetes and an improved detection of GDM. The new screening strategy and the more stringent diagnostic criteria for GDM will probably lead to an important increase in the prevalence of GDM in Belgium and might lead to logistical problems to organise an universal screening with the 2-hour 75 g oral glucose tolerance test (OGTT). We performed an audit on the current two-step screening strategy for GDM in the university hospital Leuven. Diagnosis of GDM seems sub-optimal as only two thirds of abnormal glucose challenge tests were appropriately followed by an OGTT. When the new criteria for GDM are used, the prevalence for GDM increases significantly from 3.3% to 5.7%. We feel that more data are necessary on the cost-effectiveness of an universal screening strategy using an OGTT with more stringent diagnostic criteria for GDM, especially in a population with a low background prevalence of GDM.