Testing of gestational diabetes in 12 000 pregnant women in Guangdong.

Objective To determine the cutoff value of the 50 g glucose challenge test (GCT) in gestational diabetes mellitus (GDM) and to study the threshold value of GCT, maternal age of GDM, and the rate of GDM in Guangdong. Methods Clinical data of 12 000 pregnant women between January 2005 and December 2007 in our Hospital were retrospectively analyzed. Pregnant women with abnormal blood glucose level were re-tested with 75 g OGTT. Diagnosis of gestational diabetes mellitus (GDM) and impaired glucose tolerance (IGT) were based on the criteria of National Diabetes Data Group (NDDG). Results (1) The 1 h average blood glucose level of GCT was (7.37±1.75) mmol / L. The rate of abnormal OGTT was 12.3% (GDM 5.40%, IGT 6.87% ). The abnormal rate of GCT was 35.3% when 7.8 mmol / L was used as the cutoff value. 2.8% (23 / 824) of IGT and 2.6% (17 / 648) of GDM were misdiagnosed. (2) For those women with 1 h blood glucose 11.1 mmol / L, the incidence of GDM was 74.7% (195 / 261). In which 36.8% (96 / 261) of GDM was diagnosed according to the fasting blood glucose. (3) The incidence of GDM among the women younger than 24 years old was 0.83% . The incidence of GDM was significantly lower than the others. The rate of abnormal GCT and the incidence of GDM and IGT were increased with age. Conclusion 7.8 mmol / L as the cutoff value of the GCT was appropriate for the screen of GDM in Guangdong. For those women with the level of 1 h blood glucose ≥11.1 mmol / L, repeated GCT and OGTT testing are still required. The occurrence of GDM is correlated with the age of the pregnant woman. Pregnant women of advanced maternal age should be closely monitored.