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

  1. Kirsten Graff, BS1
  1. 1Department of Emergency Medicine, Long Island Jewish Medical Center, North Shore–Long Island Jewish Healthcare System, Long Island, New York
  2. 2Department of Environmental Medicine, New York University School of Medicine, New York, New York
  1. Corresponding author: Robert Silverman, rsilverm{at}lij.edu.


OBJECTIVE Hemoglobin A1c (HbA1c) is recommended for identifying diabetes and prediabetes. 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 tolerance test (OGTT) as the criterion gold standard, we determined optimal HbA1c-screening cutoffs for undiagnosed dysglycemia in the emergency-department setting.

RESEARCH DESIGN AND METHODS 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 dysglycemia (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 (±14.9) years and mean HbA1c of 5.68% (±0.86). On the basis of an OGTT, the prevalence of previously undiagnosed prediabetes and diabetes was 31.9 and 10.5%, respectively. The optimal HbA1c-screening cutoff for prediabetes was 5.7% (area under the curve [AUC] = 0.659, sensitivity = 55%, and specificity = 71%), for dysglycemia 5.8% (AUC = 0.717, sensitivity = 57%, and specificity = 79%), and for diabetes 6.0% (AUC = 0.868, sensitivity = 77%, and specificity = 87%).

CONCLUSIONS We identified HbA1c cut points to screen for prediabetes and diabetes in an emergency-department adult population. The values coincide with published outpatient study findings and suggest that an emergency-department visit provides an opportunity for HbA1c-based dysglycemia screening.

  • Received May 24, 2010.
  • Accepted June 13, 2011.

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