Fasting plasma glucose at 24-28 weeks to screen for gestational diabetes mellitus: new evidence from China.

OBJECTIVE: To evaluate the usefulness of a fasting plasma glucose (FPG) at 24-28 weeks' gestation to screen for gestational diabetes mellitus (GDM). RESEARCH DESIGN AND METHODS: The medical records and results of a 75-g 2-h oral glucose tolerance test (OGTT) of 24,854 pregnant women without known pre-GDM attending prenatal clinics in 15 hospitals in China were examined. RESULTS: FPG cutoff value of 5.1 mmol/L identified 3,149 (12.1%) pregnant women with GDM. FPG cutoff value of 4.4 mmol/L ruled out GDM in 15,369 (38.2%) women. With use of this cutoff point, 12.2% of patients with mild GDM will be missed. The positive predictive value is 0.322, and the negative predictive value is 0.928. CONCLUSIONS: FPG at 24-28 weeks' gestation could be used as a screening test to identify GDM patients in low-resource regions. Women with an FPG between ≥4.4 and ≤5.0 mmol/L would require a 75-g OGTT to diagnose GDM. This would help to avoid approximately one-half (50.3%) of the formal 75-g OGTTs in China.