Lorraine Lipscombe, MD, MSc, FRCPC
What is the accuracy of screening with hemoglobin (Hb) A1c levels to identify patients with diabetes?
Blinded comparison of HbA1c levels with oral glucose tolerance test (OGTT) results using data from 3 datasets: Screening for Impaired Glucose Tolerance (SIGT) study, National Health and Nutrition Examination Survey (NHANES) III, and NHANES 2005 to 2006.
Atlanta (SIGT) and across the USA (NHANES studies).
4706 non-Hispanic white or black adults ≥ 18 years of age (mean age 51 y, 54% women, 27% black, mean body mass index 28.6 kg/m2) with no known history of diabetes and measures of both HbA1c and OGTT.
HbA1c levels classified using new American Diabetes Association (ADA)/International Expert Committee (IEC) criteria (diabetes = HbA1c ≥ 6.5%).
A single 75-g OGTT classified using ADA criteria: diabetes = fasting plasma glucose ≥ 126 mg/dL or 2-h plasma glucose ≥ 200 mg/dL.
Included sensitivity, specificity, and likelihood ratios (calculated from data in article).
Based on OGTT results, 5.8% of participants had diabetes. HbA1c levels ≥ 6.5% had low sensitivity but high specificity for diagnosing diabetes (Table). Non-Hispanic white persons had more false-negative results than black persons (78% vs 51%, P < 0.01).
Hemoglobin A1c levels had low sensitivity but high specificity for screening for diabetes.
Test characteristics of HbA1c levels ≥ 6.5% for diagnosing diabetes*
*Hb = hemoglobin. Diagnostic terms defined in Glossary. Sensitivity, specificity, and likelihood ratios calculated from data in article. Gold standard is oral glucose tolerance test.
Lipscombe L. HbA1c levels had low sensitivity but high specificity for screening for diabetes. Ann Intern Med. ;154:JC4–9. doi: 10.7326/0003-4819-154-8-201104190-02009
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Published: Ann Intern Med. 2011;154(8):JC4-9.
Cardiology, Coronary Risk Factors, Diabetes, Endocrine and Metabolism.
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