Fasting capillary glucose as a screening test for gestational diabetes mellitus

Objective  To evaluate fasting capillary glucose as a screening test for gestational diabetes mellitus (GDM) compared with traditional risk factors and repeated random capillary glucose measurements.
Design  Cross-sectional, population-based study.
Setting  Maternal Health Care Clinics in Örebro County, Sweden.
Population  An unselected population of women without diabetes.
Methods  Fasting capillary glucose levels were measured at gestational weeks 28–32. Random capillary glucose levels were measured four to six times during pregnancy. Traditional risk factors for GDM were registered. GDM was diagnosed using a 75-g oral glucose tolerance test.
Main outcome measures  Sensitivity, specificity, likelihood ratios.
Results  In 55 of 3616 women participating in the study, GDM was diagnosed before 34 weeks of gestation. For fasting capillary glucose cutoff values between 4.0 and 5.0 mmol/l, sensitivity was in the range between 87 and 47% and specificity between 51 and 96%. Using a combined screening model of traditional risk factors with fasting capillary glucose at various cutoff values increased the sensitivity only slightly compared with using fasting capillary glucose alone.
Conclusion  In this Swedish, unselected, low-risk population, fasting capillary glucose measurements were found to be an acceptable and useful screening test for GDM.