Are there clinical implications of racial differences in HbA1c? Yes, to not consider can do great harm

Herman, William H.

doi:10.2337/dc15-2686

Cited by 68Race, Genetics, and SocietyDiabetes Management and ResearchClinical Laboratory Practices and Quality Control

Are there clinical implications of racial differences in HbA1c? Yes, to not consider can do great harm

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Herman, William H.·2016·Diabetes Care

DOI 10.2337/dc15-2686PMC PMC4955925

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Abstract

Studies that have compared HbA1c levels by race have consistently demonstrated higher HbA1c levels in African Americans than in whites. These racial differences in HbA1c have not been explained by measured differences in glycemia, sociodemographic factors, clinical factors, access to care, or quality of care. Recently, a number of nonglycemic factors and several genetic polymorphisms that operate through nonglycemic mechanisms have been associated with HbA1c. Their distributions across racial groups and their impact on hemoglobin glycation need to be systematically explored. Thus, on the basis of evidence for racial differences in HbA1c, current clinical guidelines from the American Diabetes Association state: “It is important to take…race/ethnicity…into consideration when using the A1C to diagnose diabetes.” However, it is not clear from the guidelines how this recommendation might be actualized. So, the critical question is not whether racial differences in HbA1c exist between African Americans and whites; the important question is whether the observed differences in HbA1c level are clinically meaningful. Therefore, given the current controversy, we provide a Point-Counterpoint debate on this issue. In the point narrative below, Dr. Herman provides his argument that the failure to acknowledge that HbA1c might be a biased measure of average glycemia and an unwillingness to rigorously investigate this hypothesis will slow scientific progress and has the potential to do great harm. In the counterpoint narrative that follows Dr. Herman’s contribution, Dr. Selvin argues that there is no compelling evidence for racial differences in the validity of HbA1c as a measure of hyperglycemia and that race is a poor surrogate for differences in underlying causes of disease risk. —William T. Cefalu Editor in Chief, Diabetes Care

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A1C levels are 0.4% to 0.6% higher in Black and Hispanic individuals than in White individuals with type 2 diabetes, despite equivalent hyperglycemia.
“A1C levels may be 0.4% to 0.6% higher in Blacks and Hispanics compared with Whites, despite equivalent levels of hyperglycemia in those with T2D.11-17”
From American Association of Clinical Endocrinology Clinical Practice Guideline: Developing a Diabetes Mellitus Comprehensive Care Plan-2022 Update. (2022) · cites this paper as [13]
The paper’s Abstract reports that African Americans had higher HbA1c than whites despite comparable glucose levels; its DURABLE example gives a 0.4-percentage-point difference at the same mean glucose profile. It does not establish the stated 0.4–0.6-percentage-point range for both Black and Hispanic people with type 2 diabetes: the comparable-glucose examples discuss African Americans, and the DPP example involved impaired glucose tolerance rather than type 2 diabetes. (LLM, conf=0.87)
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In numerous cohorts and national data, Blacks have higher A1C values than Whites both with and without diabetes.
“In numerous cohorts and in national data, it has been shown that Blacks have higher A1C values than Whites in both the presence and absence of DM.12,13,133,136”
From American Association of Clinical Endocrinology Clinical Practice Guideline: Developing a Diabetes Mellitus Comprehensive Care Plan-2022 Update. (2022) · cites this paper as [13]
The paper’s Abstract reports higher HbA1c in African Americans than whites in multiple studies of people with diabetes and in the Diabetes Prevention Program, which enrolled people with impaired glucose regulation. It does not establish the claim about national data as stated; it also says the U.S. racial difference in HbA1c diminished and was eradicated between 1998 and 2010. (LLM, conf=0.82)
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Authors: Herman, W. H.
Affiliations: University of Michigan (US)
Corresponding author: Herman, William H.
ORCID: Herman, William H.
Venue: Diabetes Care
Publisher: American Diabetes Association
Published: 2016-07-12
Volume: 39
Issue: 8
Pages: 1458-1461
ISSN: 0149-5992 (ISSN-L)
1935-5548
DOI: 10.2337/dc15-2686
PMC: PMC4955925
OpenAlex: W2491582447
Cited by: 68
References: 24
Citations by year: 2026: 2 · 2025: 3 · 2024: 4 · 2023: 3 · 2022: 11 · 2021: 6 · 2020: 9 · 2019: 7 · 2018: 9 · 2017: 11 · 2016: 3
FWCI: 8.08
Type: journal article
Language: en
Open access: bronze
doi.org
Locations: Diabetes Care (publishedVersion)
Europe PMC (PubMed Central) (publishedVersion)
PubMed Central (publishedVersion)
PubMed (publishedVersion)
Funders: National Institute of Diabetes and Digestive and Kidney Diseases (P30DK092926, P30DK020572, P30DK089503)
Topics: Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Race, Genetics, and Society
Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Diabetes Management and Research
Health Sciences › Medicine › Physiology › Clinical Laboratory Practices and Quality Control
Keywords: HbA1c, racial differences, African Americans, diabetes diagnosis, glycemic variability, hemoglobin glycation, genetic polymorphism, clinical guidelines, hyperglycemia
MeSH terms: Adult, Black or African American, Blood Glucose, Diabetes Mellitus, Diet, Female, Glycated Hemoglobin, Humans, Male, Socioeconomic Factors, Exercise, Body Mass Index, White People

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Are there clinical implications of racial differences in HbA1c? Yes, to not consider can do great harm

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