Fasting capillary glucose as a screening test for gestational diabetes mellitus

Abstract

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 Orebro 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.