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. 2009 Jul 1;3(4):644-8.
doi: 10.1177/193229680900300404.

Influence of variables on hemoglobin A1c values and nonheterogeneity of hemoglobin A1c reference ranges

Trefor Higgins  1 , George Cembrowski, David Tran, Erin Lim, Julie Chan
Affiliations

Influence of variables on hemoglobin A1c values and nonheterogeneity of hemoglobin A1c reference ranges

Trefor Higgins et al. J Diabetes Sci Technol. .

Abstract

Introduction: Hemoglobin A1c (HbA1c) values are influenced by analytical interferences such as HbF and hemoglobin variants and clinical factors such as increased red cell turnover. Although less well-known, demographic factors such as race, age, and sex also influence HbA1c values. The HbA1c reference range should be homogenous in the United States based on the use of National Glycohemoglobin Standardization Program certified methods and the recommendations in the National Academy of Clinical Biochemistry guidelines.

Methods: Data on age, race, sex, HbA1c, and glucose values were extracted from the National Health and Nutrition Examination study for a 3 year period. A search for reference range data for laboratories in the United States was performed using the Google search engine.

Results: Extracted data agree with published data on the influence of age, sex, and smoking status on HbA1c values. There is substantial heterogeneity in HbA1c reference ranges in laboratories in the United States.

Conclusion: Age, sex, and smoking status influence HbA1c values. Despite standardization of HbA1c methods and published recommendations, there is wide heterogeneity in HbA1c reference ranges in the United States.

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Figures

Figure 1.
Figure 1.
Hemoglobin A1c reference ranges for laboratories in the United States. The NACB-recommended reference range is in black.
Figure 2.
Figure 2.
Hemoglobin A1c value (y axis) plotted against age (x axis) for males using different population percentiles in the (A) Mexican American (MMA), (B) non-Hispanic white (MNHW), and (C) non-Hispanic black (MNHB) groups from data in the 1999 to 2002 NHANES study, with fasting glucose values less than or equal to 6.0 mmol/liter.
Figure 3.
Figure 3.
Hemoglobin A1c value (y axis) plotted against age (x axis) for females using different population percentiles in the (A) Mexican American (FMA), (B) non-Hispanic white (FNHW), and (C) non-Hispanic black (FNHB) groups from data in the 1999 to 2002 NHANES study, with fasting glucose values less than or equal to 6.0 mmol/liter.
Figure 4.
Figure 4.
Hemoglobin A1c levels in everyday smokers (ED), most-day smokers (MD), and nonsmokers (0) from the NHANES 1999–2002 data on patients with fasting glucose values less than 7.1 mmol/liter.
See this image and copyright information in PMC

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