Applicability of a combination of hemoglobin A1c and fasting plasma glucose in population-based prediabetes screening

Ike S. Okosun, Monique Davis-Smith, J. Paul Seale, John Ngulefac

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Background: The purpose of this study is to determine: (i) the concordance between a combination of hemoglobinA1c (HbA1c) and fasting plasma glucose (FPG) (HbA1c+FPG) and a combination of FPG and 2-h plasma glucose (2hPG) (FPG+2hPG); and (ii) whether substituting FPG+2hPG with HbA1c+FPG can enhance the detection of prediabetes in diabetes-free non-Hispanic Whites, non-Hispanic Blacks, and Mexican-Americans adults. Methods: Data (n=1376) from the 2007 to 2008 U.S. National Health and Nutrition Examination Surveys were used for this investigation. Prediabetes cut points were determined using 5.7-6.4%, 100-125, and 140-199mg/dL for HbA1c, FPG, and 2hPG, respectively. Concordances between HbA1c and FPG, HbA1c and 2hPG, HbA1c+FPG and FPG+2hPG in screening for undiagnosed prediabetes were determined using sensitivity, specificity, and positive and negative likelihood ratios. Results: The overall concordance between HbA1c+FPG and FPG+2hPG in screening for prediabetes was high, as indicated by a sensitivity of 92.4% (95% CI=90.5-94.5) and specificity of 84.1% (81.2-87.0). The application of HbA1c+FPG was associated with a higher prevalence of prediabetes compared to FPG+2hPG. Compared with FPG+2hPG, screening with HbA1c+FPG was associated with 3.2%, 24.3%, and 4.2% relative increases in the identification of prediabetes in nondiabetic non-Hispanic Whites, non-Hispanic Blacks and Mexican-Americans, respectively. Conclusions: The enhanced prevalence of prediabetes using HbA1c+FPG compared with FPG+2hPG calls for the need to redefine at a more basic and practical level how to apply HbA1c in screening for prediabetes. A redefined HbA1c that incorporates FPG, age, race/ethnicity, and body mass index may be a better way to use HbA1c in population-based and clinical settings.

Original languageEnglish (US)
Pages (from-to)407-416
Number of pages10
JournalJournal of Diabetes
Issue number4
StatePublished - Dec 2012
Externally publishedYes


  • Diabetes mellitus
  • Glycated hemoglobin
  • Glycemia
  • Glycemic index
  • Impaired glucose tolerance

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism


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