title: Hemoglobin a1c may be an inadequate diagnostic tool for diabetes mellitus in anemic subjects.
abstract: BACKGROUND
  Recently, a hemoglobin A1c (HbA1c) level of 6.5% has been determined to be a criterion for diabetes mellitus (DM), and it is a widely used marker for the diagnosis of DM. However, HbA1c may be influenced by a number of factors. Anemia is one of the most prevalent diseases with an influence on HbA1c; however, its effect on HbA1c varies based on the variable pathophysiology of anemia. The aim of this study was to determine the effect of anemia on HbA1c levels.
  
  
  METHODS
  Anemic subjects (n=112) and age- and sex-matched controls (n=217) who were drug naive and suspected of having DM were enrolled. The subjects underwent an oral glucose tolerance test and HbA1c simultaneously. We compared mean HbA1c and its sensitivity and specificity for diagnosing DM between each subgroup.
  
  
  RESULTS
  Clinical characteristics were found to be similar between each subgroup. Also, when glucose levels were within the normal range, the difference in mean HbA1c was not significant (P=0.580). However, when plasma glucose levels were above the diagnostic cutoff for prediabetes and DM, the mean HbA1c of the anemic subgroup was modestly higher than in the nonanemic group. The specificity of HbA1c for diagnosis of DM was significantly lower in the anemic subgroup (P<0.05).
  
  
  CONCLUSIONS
  These results suggest that the diagnostic significance of HbA1c might be limited in anemic patients.
authors.affiliation: Department of Endocrinology and Metabolism, Kyung Hee University School of Medicine, Seoul, Korea.
authors.forename: Jung Il
authors.initials: JI
authors.lastname: Son
authors.forename: Sang Youl
authors.initials: SY
authors.lastname: Rhee
authors.forename: Jeong-Taek
authors.initials: JT
authors.lastname: Woo
authors.forename: Jin Kyung
authors.initials: JK
authors.lastname: Hwang
authors.forename: Sang Ouk
authors.initials: SO
authors.lastname: Chin
authors.forename: Suk
authors.initials: S
authors.lastname: Chon
authors.forename: Seungjoon
authors.initials: S
authors.lastname: Oh
authors.forename: Sung Woon
authors.initials: SW
authors.lastname: Kim
authors.forename: Young Seol
authors.initials: YS
authors.lastname: Kim
keywords: Anemia; Diabetes mellitus; Diagnosis; Hemoglobin A, glycosylated