Hemoglobin A1c as a Screen for Previously Undiagnosed Prediabetes and Diabetes in an Acute-Care Setting

OBJECTIVE—Hemoglobin A1c (HbA1c) is recommended for identifying diabetes and predi-abetes. Because HbA1c does not fluctuate with recent eating or acute illness, it can be measured in a variety of clinical settings. Although outpatient studies identified HbA1c-screening cutoff values for diabetes and prediabetes, HbA1c-screening thresholds have not been determined for acute-care settings. Using follow-up fasting blood glucose (FBG) and the 2-h oral glucose toler-ance test (OGTT) as the criterion gold standard, we determined optimal HbA1c-screening cutoffs for undiagnosed dysglycemia in the emergency department setting. RESEARCH DESIGN ANDMETHODS—This was a prospective observational study of adults aged $18 years with no known history of hyperglycemia presenting to an emergency department with acute illness. Outpatient FBS and 2-h OGTT were performed after recovery from the acute illness, resulting in diagnostic categorizations of prediabetes, diabetes, and dys-glycemia (prediabetes or diabetes). Optimal cutoffs were determined and performance data identified for cut points. RESULTS—A total of 618 patients were included, with a mean age of 49.7 (614.9) years and mean HbA1c of 5.68 % (60.86). On the basis of an OGTT, the prevalence of previousl