Results from screening for gestational diabetes mellitus in a Danish county.

Objective: To examine the complications in gestational diabetes mellitus with special reference to the significance of the threshold for the oral glucose tolerance test (OGTT, plasma glucose > or = 7.8 mmol/l (equivalent to blood glucose 6.9 mmol/l) (WHO criteria) or blood glucose > 6.7 mmol/l (local criteria) after 2 h 75 g oral glucose load).

Design: Prospective descriptive study.

Setting: From April 1, 1995 to April 1, 1997 a screening for gestational diabetes mellitus (GDM) according to the recommendations from the Danish board of health was performed in Ribe county.

Subjects: Pregnant women in Ribe county (n = 6158).

Main Outcome Measures: Complications during pregnancy and the outcome.

Results: Two hundred and twenty (3.6%) women had GDM by the local selection criteria and 2.8% according to the WHO criteria. The study revealed a significantly increased frequency of malformations (7.3% vs. 1.2%, p < 0.0001) and preeclampsia (15.5% vs. 1%, p < 0.0001) in the group with GDM independent of selection criteria (obesity vs. family history and glucosuria). The frequency of preeclampsia appeared higher in the group with obesity (p = 0.040). Malformations appeared with identical frequency in the groups with OGGT threshold higher than blood glucose 6.9 mmol/l (plasma glucose 7.8 mmol/l) (WHO criteria) and with blood glucose between 6.7 and 6.9 mmol/l, whereas preeclampsia did not occur with higher frequency in the latter group.

Conclusion: Complications appear frequently in women with an abnormal OGGT, and obesity predisposes to preeclampsia. The use of the WHO criteria for screening for GDM would miss a number of women with complications.