Objectives: In the face of the ongoing discussion on the criteria for the diagnosis of gestational diabetes (GDM), we aimed to examine whether the criteria of the 4^th International-Workshop-Conference of GDM (WC) better select women and children at risk than the WHO-criteria.

Design and Setting: Prospective longitudinal open study in 5 tertiary care centers in Austria

Patients and outcome measures: The impact of risk factors, different thresholds (WC vs. WHO) and numbers of abnormal glucose values (WC) during the 2h-75g-oGTT on fetal/neonatal complications and maternal postpartum glucose tolerance was studied in 1466 pregnant women. Women were treated if at least one value according to the WC (GDM-WC1) was met or exceeded.

Results: 46% of all women had GDM-WC1, while 29% had GDM-WHO. 21% of all women had two or three abnormal values according to WC-criteria (GDM-WC2). 85% of the GDM-WHO were also identified by GDM-WC1. Previous GDM (OR 2.9), glucosuria (OR 2.4), preconceptual overweight/obesity (OR 2.3), age 30yrs (OR 1.9) and large-for- gestational age (LGA) fetus (OR 1.8) were the best independent predictors of the occurrence of GDM. Previous GDM (OR 4.4) and overweight/obesity (OR 4.0) also independently predicted diabetes postpartum. GDM-WC1 had a higher rate of obstetrical complications (LGA-neonates, neonatal hypoglycemia, C-sections; p<0.001) and impaired postpartum glucose tolerance (p<0.0001) than GDM-WHO.

Conclusion: These results suggest to use the more stringent WC-criteria for the diagnosis of GDM with the initiation of therapy in case of one fasting or stimulated abnormal glucose value, as these criteria detected more LGA neonates with hypoglycaemia and mothers with impaired postpartum glucose metabolism than the WHO-criteria.