Hemoglobin A1c May Be an Inadequate Diagnostic Tool for Diabetes Mellitus in Anemic Subjects

Abstract

BackgroundRecently, 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.MethodsAnemic 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.ResultsClinical 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).ConclusionThese results suggest that the diagnostic significance of HbA1c might be limited in anemic patients.

Derivation and validation of an HbA1c optimal cutoff for diagnosing prediabetes in a South African mixed ancestry population

“…HbA1c may be unreliable to diagnose prediabetes and diabetes in anaemic patients. Son et al found that anaemic subjects had a higher HbA1c level and suggested that the diagnostic significance of HbA1c may be limited in them [31]. This higher HbA1c was more pronounced in subjects with higher glucose levels.…”

The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review

“…They also suggest that IDA changes the quaternary structure of Hb leading to increased glycation. [15] grouped 329 Korean participants, not previously known to have diabetes, by diabetes status according to OGTT results. Participants were grouped as normal, prediabetes or diabetes, HbA 1c levels were then compared in each group for both anaemic and non-anaemic participants.…”

Glycated haemoglobin and iron deficiency anaemia: a case‐control study

“…Recently, a review described the controversies concerning the role of anaemia on HbA 1c . In fact, some studies suggested that in patients with or without diabetes, iron deficiency anaemia (IDA) is associated with higher HbA 1c levels . Other works reported that, in patients not affected by diabetes but with iron deficiency, HbA 1c concentrations had no significant changes .…”

“…observed that HbA 1c level in subjects with IDA was significantly lower than in the control group . Few works evaluated the relationship between erythrocyte indices and HbA 1c levels; in particular, statistical analyses were unclear or not assessed . Koga et al .…”