Cut-off values of laboratory measurements of capillary blood glucose in a glucose challenge test. Evaluation of 250 cases

The aim of the present investigation was to select the most suitable threshold in a glucose challenge test using capillary glucose measured in the laboratory. Two hundred and fifty consecutive pregnant women who attended the antenatal clinic of the Department of Obstetrics and Gynecology of Ferrara University in 1991 were tested at 27.4 ± 2.8 weeks of pregnancy. One week later every patient had a confirmatory glucose tolerance test. Receiver operating characteristic curve analysis technique was used to select cut-off values. A glucose concentration of 8.3 mmol/l (150 mg/dl) was the best threshold in patients studied. This value is higher than that recommended for venous plasma and lower than those proposed for capillary glucose measured by reflectance meters.