Cited by 478Diabetes Management and ResearchDiabetes Treatment and ManagementDiabetes Management and Education

The fallacy of average: how using HbA1c alone to assess glycemic control can be misleading

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Beck, Roy W., Connor, Crystal G., Mullen, Deborah M., Wesley, David M., Bergenstal, Richard M.·2017·Diabetes Care

Abstract

HbA1c is a valuable metric for comparing treatment groups in a randomized trial, for assessing glycemic trends in a population over time, or for cross-sectional comparisons of glycemic control in different populations. However, what is not widely appreciated is that HbA1c may not be a good indicator of an individual patient’s glycemic control because of the wide range of mean glucose concentrations and glucose profiles that can be associated with a given HbA1c level. To illustrate this point, we plotted mean glucose measured with continuous glucose monitoring (CGM) versus central laboratory–measured HbA1c in 387 participants in three randomized trials, showing that not infrequently HbA1c may underestimate or overestimate mean glucose, sometimes substantially. Thus, if HbA1c is to be used to assess glycemic control, it is imperative to know the patient’s actual mean glucose to understand how well HbA1c is an indicator of the patient’s glycemic control. With knowledge of the mean glucose, an estimated HbA1c (eA1C) can be calculated with the formula provided in this article to compare with the measured HbA1c. Estimating glycemic control from HbA1c alone is in essence applying a population average to an individual, which can be misleading. Thus, a patient’s CGM glucose profile has considerable value for optimizing his or her diabetes management. In this era of personalized, precision medicine, there are few better examples with respect to the fallacy of applying a population average to a specific patient rather than using specific information about the patient to determine the optimal approach to treatment.

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  1. [1]Rose T. The End of Average: How We Succeed in a World That Values Sameness. New York, Harper Collins, 2015 [Google Scholar]
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Authors
Beck, R. W., Connor, C. G., Mullen, D. M., Wesley, D. M., & Bergenstal, R. M.
Affiliations
  • Jaeb Center for Health Research (US)
  • Park Nicollet Health Services (US)
Corresponding author
Beck, Roy W.
Venue
Diabetes Care
Published
2017-07-11
Volume
40
Issue
8
Pages
994-999
ISSN
  • 0149-5992 (ISSN-L)
  • 1935-5548
OpenAlex
W2739310415
Cited by
477
References
29
Citations by year
2026: 44 · 2025: 47 · 2024: 62 · 2023: 48 · 2022: 67 · 2021: 75 · 2020: 56 · 2019: 43 · 2018: 28 · 2017: 7
FWCI
28.99
Type
journal article
Language
en
Open access
Locations
  • Diabetes Care (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Leona M. and Harry B. Helmsley Charitable Trust
  • The National Institute of Diabetes and Digestive and Kidney Diseases (DK108611)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Management and Research
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Treatment and Management
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Management and Education
Keywords
HbA1c, glycemic control, mean blood glucose, continuous glucose monitoring, HbA1c estimation, diabetes management, personalized medicine, glucose profile
MeSH terms
Adult, Aged, Blood Glucose, Cross-Sectional Studies, Diabetes Mellitus, Type 1, Diabetes Mellitus, Type 2, Female, Glycated Hemoglobin, Humans, Male, Middle Aged, Blood Glucose Self-Monitoring, Disease Management, Young Adult, Precision Medicine

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