DIAGNOSING GESTATIONAL DIABETES-MELLITUS - USE OF A GLUCOSE SCREEN WITHOUT ADMINISTERING THE GLUCOSE-TOLERANCE TEST

Objective: To determine if a 1-hour glucose screen value could be iden tified, above which gestational diabetes mellitus could be diagnosed w ithout the 3-hour oral glucose tolerance test (GTT). Methods: Demograp hic, historic, obstetric, and neonatal data from 514 singleton pregnan cies with glucose screen values at least 140 mg/dL followed by a GTT w ere reviewed (312 patients with normal GTTs and 202 with gestational d iabetes mellitus). Statistical analyses used chi(2), Fisher exact, Stu dent t, and Mann-Whitney tests. After determining the optimal glucose screen cutoff point using receiver operating characteristic curve anal yses, patients were regrouped according to this value and analyzed fur ther. Results: The optimal cutoff point for the upper limit of the glu cose screen was determined to be 186 mg/dL (95.9% specificity, 98.2% n egative predictive value, 36.1% sensitivity, and 19.6% positive predic tive value). Comparison of patients with elevated screens and normal G TTs versus those with gestational diabetes revealed significant differ ences only regarding a history of gestational diabetes mellitus and ne onatal hypoglycemia in the studied pregnancy. Those with screens great er than 185 mg/dL behaved like diabetic patients and, when compared wi th subjects with screens of 140-185 mg/dL, also had a significantly gr eater proportion of large for gestational age infants. Conclusion: Pat ients with 1-hour glucose screens greater than 185 mg/dL have a high p robability of gestational diabetes mellitus and the diagnosis can be m ade without the GTT. Using this approach could allow prompt initiation of therapy without the inconvenience and discomfort of the GTT.