ABSTRACT
The ability of HbA1c was evaluated in the diagnosis of gestational diabetes mellitus (GDM) and for the implications of its use in clinical practice. A total of 339 pregnant women with an estimated gestational age of 24-28 weeks were evaluated for GDM using an oral glucose tolerance test (OGTT) based on International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria. A ROC curve was drawn to determine the sensitivity and specificity of HbA1c in detecting GDM. An HbA1c cut-off value of ≥ 5.2% had sensitivity of 64.15% and specificity of 67.48% in diagnosing GDM, and a positive predictive value of 26.77%. Using two cut-offs in the 'rule-in and rule-out' algorithm, 94.4% of the GDM cases would have been detected but 33% (43 of the 130) women would had been misclassified. HbA1c is not suitable to use alone for the diagnosis of GDM and is not useful in decreasing the need for OGT testing.
