Optimal hemoglobin A1C Cutoff Value for Diagnosing type 2 diabetes mellitus in Korean adults

Hyejin Lee, Jee Young Oh, Yeon Ah Sung, Dong Jun Kim, Sung Hoon Kim, Sin Gon Kim, Sungdae Moon, Ie Byung Park, Eun Jung Rhee, Choon Hee Chung, Byung Joon Kim, Bon Jeong Ku

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34 Scopus citations


Commonly used tests for the diagnosis of diabetes include measurements of fasting plasma glucose levels and the oral glucose tolerance test (OGTT). Recently, a hemoglobin A1C (A1C) level of 6.5% has been included as a criterion for diabetes diagnosis by the American Diabetes Association. We aimed to determine appropriate A1C cutoff values for identifying patients with diabetes or prediabetes, including impaired glucose tolerance and impaired fasting glucose among Korean adults and to determine whether these cutoffs vary according to age. We recruited 4616 adults without a history of diabetes from 10 university hospitals. A 75-g OGTT and A1C sampling were performed in all examinees. Pointwise area under the receiver operating characteristic curve was used to evaluate the diagnostic accuracy of the A1C cutoff. An A1C threshold of 6.1% proved to be the optimal limit for diagnosing diabetes, with 63.8% sensitivity and 88.1% specificity. The cutoff value increased with age (5.9% in 18-39 years, 6.2% in 40-64 years, and 6.4% in older than 65 years) and were similar for men and women. An A1C cutoff of 5.7% had reasonable sensitivity (48.6%) and specificity (65.7%) for the identification of prediabetes. Further prospective studies should be carried out to determine whether the application of age-specific diagnostic criteria is appropriate.

Original languageEnglish
Pages (from-to)231-236
Number of pages6
JournalDiabetes Research and Clinical Practice
Issue number2
StatePublished - Feb 2013

Bibliographical note

Funding Information:
This work was funded from the Korean Diabetes Association .


  • Diabetes
  • Diagnosis
  • HbA1C


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