Background Gestational diabetes mellitus (GDM) is a frequent complication in pregnancy, however there is lacking agreement on international CPG on the best screening strategy: whom, when and how to screen. Following the HAPO study, the International Association of Diabetes and Pregnancy Study Group (IADPSG) recommended a new strategy consisting on a 1-step 2-hour 75 g. oral glucose tolerance test.

Objectives To systematically review the evidence that compares alternative tests for diagnosis of GDM, in terms of maternal and infant health and costs.

Methods MEDLINE, EMBASE, EBM reviews and NHS EED were searched. Studies comparing the IADPSG guidelines with other strategies were retrieved. Besides, recommendations currently in place in different countries were summarised.

Results Eleven studies were selected. The results showed that the IADPSG criteria nearly threefold GDM prevalence. Women who fulfilled IADPSG criteria but were normal using other criteria experienced significantly higher adverse outcomes (macrosomia, preterm delivery, neonatal hypoglycaemia and pre-eclampsia). Although the IADPSG screening strategy was more costly, considering the long-term maternal benefits and the neonatal outcomes it might be cost-effective.

Discussion Implementing the IADPSG criteria will increase GDM diagnosis and this may pose a strain on health care systems, but it is also an opportunity to reduce adverse outcomes for mother and child. In fact, the IADPSG strategy appeared to be cost-effective strategy under certain conditions. Further large well-designed trials are needed to determine the best strategy.

Implications for Guideline Developers/Users Considering the high inconsistency across guidelines the new IADPSG screening strategy may outdate current strategies proposed on CPG.