To determine the sensitivity and specificity of the 50-g 1-h glucose screening test (GST) for hyperglycemia established in a home-monitored glucose profile (HGP) from blood sampled 1 h after each of the main meals on the following day, we prospectively studied 415 pregnant women at increased risk for gestational diabetes and compared 1 GST with 1 HGP. At the commonly recommended GST threshold of 7.8 mmol/l and an HGP threshold of 7.0 mmol/l, the sensitivity of the GST was 27%, the specificity 89%, and the likelihood ratio for a positive test 2.4. Therefore, we conclude that the 50-g 1-h glucose screening test discriminates poorly between pregnant women with and without postprandial hyperglycemia.