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[Indication for the HbA1c assay, it's interpretation and sources of error]

Satu Vehkavaara1

  • 1HYKS:n endokrinologian klinikka, PL 340, 00029 HUS.

Duodecim; Laaketieteellinen Aikakauskirja
|August 3, 2011
PubMed

Insights

Glycated hemoglobin (HbA1c) monitoring is crucial for diabetes management. While HbA1c shows promise for diagnosing diabetes, it is less reliable than the oral glucose tolerance test (OGTT) for early detection.

Area of Science:

  • Endocrinology
  • Clinical Chemistry
  • Diabetes Research

Background:

  • Glycemic control is traditionally monitored using glycated hemoglobin (HbA1c) alongside self-monitoring of blood glucose.
  • Recent proposals suggest using HbA1c for diabetes diagnosis, either independently or combined with the oral glucose tolerance test (OGTT).

Purpose of the Study:

  • To evaluate the utility of HbA1c in diabetes diagnosis, particularly in early stages.
  • To identify factors affecting HbA1c accuracy and propose diagnostic criteria.

Main Methods:

  • Review of existing diagnostic protocols for diabetes.
  • Analysis of HbA1c assay limitations, including the impact of red blood cell lifespan.
  • Evaluation of proposed HbA1c diagnostic criteria.

Main Results:

  • The HbA1c assay is a less sensitive method than OGTT for diagnosing early diabetes.
  • Shortened red blood cell lifespan is a significant factor causing falsely lowered HbA1c levels.
  • Proposed diagnostic criteria for type 2 diabetes include HbA1c ≥ 6.5% in asymptomatic individuals (measured twice) or once with overt hyperglycemia.

Conclusions:

  • HbA1c is a valuable tool for monitoring glucose homeostasis but has limitations as a standalone diagnostic test for early diabetes.
  • The OGTT remains a more robust method for diagnosing early diabetes.
  • Refined criteria incorporating HbA1c measurement frequency and clinical presentation are suggested for type 2 diabetes diagnosis.

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