Limitations of glycosylated haemoglobin as an index of glucose intolerance

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Published on: January 7, 2018

C Snehalatha1, A Ramachandran, K Satyavani

  • 1Diabetes Research Centre, Royapuram, Chennai, India. diabetes.research@gems.vsnl.net.in

Diabetes Research and Clinical Practice
|February 12, 2000
PubMed

Insights

This study determined a normal glycosylated hemoglobin (HbA1c) cut-off for South Indians, finding it has limitations in diagnosing glucose intolerance due to unexplained variations. While HbA1c > or = 6.0% shows reasonable sensitivity and specificity, it

Area of Science:

  • Endocrinology and Metabolism
  • Clinical Chemistry
  • Public Health

Background:

  • Glycosylated hemoglobin (HbA1c) is a key marker for glucose control.
  • Establishing population-specific normal cut-off values is crucial for accurate diagnosis.
  • Previous studies have shown variability in HbA1c across different ethnic groups.

Purpose of the Study:

  • To establish a normal cut-off value for HbA1c in South Indian subjects.
  • To evaluate the diagnostic utility of HbA1c in identifying glucose intolerance using WHO and ADA criteria.
  • To assess the correlation between HbA1c and plasma glucose levels in this population.

Main Methods:

  • HbA1c levels were measured in 1261 subjects without a history of diabetes using an immunoturbidimetric assay.
  • Oral glucose tolerance tests (OGTT) were performed to categorize glucose tolerance.
  • Receiver Operating Characteristic (ROC) analysis was employed to determine sensitivity and specificity.

Main Results:

  • A cut-off value of HbA1c > or = 6.0% demonstrated a sensitivity of 88.5% and specificity of 62.8% for WHO criteria (2-h plasma glucose > or = 200 mg/dl).
  • Using ADA criteria (fasting plasma glucose > 125 mg/dl), the same cut-off yielded 85.2% sensitivity and 61.2% specificity.
  • Over 35% of the variation in HbA1c was not explained by fasting or 2-hour post-glucose plasma levels, indicating significant inter-individual variability.

Conclusions:

  • HbA1c > or = 6.0% offers reasonable sensitivity and specificity for diagnosing glucose intolerance in South Indians based on established criteria.
  • Significant unexplained inter-individual variations in HbA1c, even within the normoglycemic range, limit its sole diagnostic utility.
  • Further research is needed to understand the factors contributing to HbA1c variability and refine diagnostic approaches.

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