[Evaluation of the glucose screening retest during pregnancy]

Abstract

Objective: To evaluate of the glucose screening retest for gestational diabetes mellitus (GDM) during pregnancy.

Methods: A retrospective analysis of 714 pregnant women screened for GDM, between December 1, 2001, and December 31, 2002, was performed. The first glucose challenge test (GCT) was performed in 16 - 27 week and retested in 28 - 38 week. Diagnosis of GDM was based on the criteria of Dong. NDDG criteria was also discussed.

Results: (1) 1-hour glucose value of 50 g GCT >or= 7.8 mmol/L was set as abnormal. The first 50 g GCT abnormal rate was 26.6% (190/714), and the retest abnormal rate was 35.2% (225/639). The mean age of pregnant women in 50 g GCT positive group was significantly higher than that in the negative group (P < 0.05), but there was no significant difference in family history and body mass index (BMI) between the two groups. Both the mean birth weight and the incidence of macrosomia of second 50 g GCT abnormal group were significantly higher than those in the normal group (P < 0.05). (2) By the criteria of Dong, 28 women were found to have GDM and 40 have IGT (impaired glucose tolerance) by the first 50 g GCT. New added cases included 15 GDM and 27 IGT by the retest 50 g GCT. By NDDG criteria, 14 GDM and 24 IGT cases were diagnosed by the first 50 g GCT, 5 GDM and 14 IGT cases by retest GCT. (3) The 1-hour blood glucose value [(7.3 +/- 1.6) mmol/L] in second 50 g GCT were significantly higher than those in first 50 g GCT [(6.9 +/- 1.8) mmol/L]. The results of 50 g GCT of two times were consistent in 68.1% women (normal/normal and abnormal/abnormal). There were 376 (52.7%) women whose 1-hour glucose value of the first 50 g GCT <or= 6.8 mmol/L. Among them neither GDM nor IGT were found by retest GCT. If the 1-hour glucose value of first 50 g GCT < 7.8 mmol/L (n = 524), there were 4 cases GDM and 17 cases IGT by the criteria of Dong by retest of 50 g GCT, but no GDM and only 7 cases IGT were found by NDDG criteria.

Conclusions: (1) Screening for GDM should be done for all pregnant women especially in big city. (2) If the NDDG criteria were used, the retest should be done for the women whose first 50 g GCT >or= 7.8 mmol/L, and the 75 g OGTT should be done directly. (3) Maternal age appears to be the most important risk factor for GDM.