Yogish C. Kudva, MD; Ananda Basu, MD
In patients without diabetes, what is the agreement of hemoglobin (Hb) A1c and fasting plasma glucose (FPG) tests and what is the accuracy of elevated HbA1c levels (5.7% to 6.4%) for diagnosis of prediabetes?
Comparison of elevated HbA1c levels (5.7% to 6.4%) with FPG test results.
7029 noninstitutionalized civilian adults ≥ 20 years of age (mean age 45 y, 52% women) who participated in the National Health and Nutrition Examination Survey between 1999 and 2006 (inclusive). Exclusion criteria included previous diabetes diagnosis, FPG ≥ 126 mg/dL (6.99 mmol/L), HbA1c ≥ 6.5%, and missing FPG or HbA1c measurements.
HbA1c measured with high-performance liquid chromatography.
Prediabetes was defined as FPG levels of 100 to 125 mg/dL (5.5 to 6.9 mmol/L) measured in the morning after a 9- to 24-hour fast.
Included agreement of HbA1c and FPG results and sensitivity and specificity of HbA1c.
HbA1c and FPG results were in agreement for diagnosis of prediabetes in only 7.7% of patients; 20.5% of patients were diagnosed with prediabetes by the FPG test but not the HbA1c test and 4.9% by the HbA1c test only. Sensitivity of elevated HbA1c levels was 27%, and specificity was 93% (Table).
In patients without diabetes, agreement between hemoglobin A1c and fasting plasma glucose tests for diagnosis of prediabetes was very low. The accuracy of the hemoglobin A1c range of 5.7% to 6.4% had low sensitivity and high specificity for diagnosis of prediabetes.
Diagnostic properties of elevated hemoglobin A1c (5.7% to 6.4%) for diagnosing prediabetes*
*Diagnostic terms defined in Glossary. LRs calculated from data in article.
Kudva YC, Basu A. Elevated HbA1c levels (5.7% to 6.4%) had low accuracy for diagnosing prediabetes. Ann Intern Med. ;154:JC3–11. doi: 10.7326/0003-4819-154-6-201103150-02011
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Published: Ann Intern Med. 2011;154(6):JC3-11.
Cardiology, Coronary Risk Factors, Diabetes, Endocrine and Metabolism.
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