Diagnostic accuracy of glycohemoglobin A1c (HbA1c) for postprandial hyperglycemia was equivalent to that of fasting blood glucose

J Clin Epidemiol. 2005 Oct;58(10):1052-7. doi: 10.1016/j.jclinepi.2005.01.019.


Objectives: To compare the sensitivity, specificity, and total accuracy of an HbA1c of > or =6.5% in the detection of hyperglycemia (PPHG) relative to those of a fasting blood glucose (FBG) of > or =7.0 mmol/L.

Methods: A total of 6,010 subjects (2,987 men and 3,023 women) living or working in Kasugai, Japan, underwent a medical checkup at Kasugai City Medical Care Center between April 2001 and March 2002. For the 91 subjects who had either a FBG of > or =7.0 mmol/L or an HbA1c of > or =6.5%, a 75-g oral glucose tolerance test was performed to confirm or exclude PPHG. We calculated the true- and false-positive odds ratios to evaluate the sensitivity and specificity of HbA1c relative to FBG, and compared the overall accuracy by calculating the conditional relative odds ratio (CROR).

Results: Among the 91 subjects, the true- and false-positive odds ratios were 0.43 (95% CI 0.26-0.69) and 0.40 (0.13-1.27) (Fisher's exact test, P < .090), respectively; the CROR was 1.07 (95% CI 0.30-3.75).

Conclusions: Although the HbA1c test was marginally more specific but less sensitive than the FBG test, at the given cutoff points the accuracies of two tests were equivalent.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Adult
  • Aged
  • Anthropometry
  • Biomarkers / blood
  • Blood Glucose / analysis*
  • Diabetes Mellitus, Type 2 / diagnosis*
  • False Positive Reactions
  • Fasting / blood
  • Female
  • Glucose Tolerance Test
  • Glycated Hemoglobin / analysis*
  • Humans
  • Hyperglycemia / diagnosis*
  • Male
  • Middle Aged
  • Postprandial Period
  • Sensitivity and Specificity


  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A