Implications of the Hemoglobin Glycation Index on the Diagnosis of Prediabetes and Diabetes

Daniel S. Hsia, Neda Rasouli, Anastassios G. Pittas, Christine W. Lary, Anne Peters, Michael R. Lewis, Sangeeta R. Kashyap, Karen C. Johnson, Erin S. Leblanc, Lawrence S. Phillips, James M. Hempe, Cyrus V. Desouza, Irwin Brodsky, Lisa Ceglia, Chhavi Chadha, Ranee Chatterjee, Bess Dawson-Hughes, Cyruse Desouza, Rowena Dolor, John ForeytAdline Ghazi, Sun Kim, Emilia Liao, Saul Malozowski, Lisa M. Neff, Patrick O'neil, Jean Park, Richard Pratley, Philip Raskin, David Robbins, Clifford Rosen, Vanita R. Aroda, Patricia Sheehan, Myrlene A. Staten, William C. Knowler

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Objective: Fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG) from a 75-g oral glucose tolerance test (OGTT) and glycated hemoglobin (HbA1c) can lead to different results when diagnosing prediabetes and diabetes. The Hemoglobin Glycation Index (HGI) quantifies the interindividual variation in glycation resulting in discrepancies between FPG and HbA1c. We used data from the Vitamin D and Type 2 Diabetes (D2d) study to calculate HGI, to identify HGI-associated variables, and to determine how HGI affects prediabetes and diabetes diagnosis. Measurements: A linear regression equation [HbA1c (%) = 0.0164 × FPG (mg/dL) + 4.2] was derived using the screening cohort (n = 6829) and applied to calculate predicted HbA1c. This was subtracted from the observed HbA1c to determine HGI in the baseline cohort with 2hPG data (n = 3945). Baseline variables plus prediabetes and diabetes diagnosis by FPG, HbA1c, and 2hPG were compared among low, moderate, and high HGI subgroups. Results: The proportion of women and Black/African American individuals increased from low to high HGI subgroups. Mean FPG decreased and mean HbA1c increased from low to high HGI subgroups, consistent with the HGI calculation; however, mean 2hPG was not significantly different among HGI subgroups. Conclusions: High HGI was associated with Black race and female sex as reported previously. The observation that 2hPG was not different across HGI subgroups suggests that variation in postprandial glucose is not a significant source of population variation in HGI. Exclusive use of HbA1c for diagnosis will classify more Black individuals and women as having prediabetes compared with using FPG or 2hPG.

Original languageEnglish (US)
Article numberdgaa029
JournalJournal of Clinical Endocrinology and Metabolism
Issue number3
StatePublished - Jan 8 2020


  • diagnosis
  • hemoglobin glycation
  • observational study
  • oral glucose tolerance test
  • prediabetes
  • type 2

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical


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