A1C May Be Less Accurate Measure of Diabetes in African Americans with Common Sickle Cell Trait

MedicalResearch.com Interview with:
Mary E. Lacy, MPH

Department of Epidemiology
Brown University School of Public Health
Providence, RI

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Hemoglobin A1c (A1C) is a blood test that is used to screen for and monitor diabetes. It measures average blood sugar control over the past 2-3 months.

A person with sickle cell trait is a carrier for sickle cell disease but often doesn’t have any clinical symptoms. African Americans are more likely than Whites to have diabetes and are more likely to have sickle cell trait. In this article we examined if A1C can be interpreted in the same way in people with and without sickle cell trait.

We found that, despite similar results on other measures of blood sugar control, people with sickle cell trait had lower A1C results than people without sickle cell trait. This means that A1C may underestimate diabetes risk in people with sickle cell trait.
We also found that, when using standard A1C cutoffs to screen for disease prevalence, we identified 40% fewer cases of prediabetes and 48% fewer cases of diabetes in individuals with sickle cell trait than in those without sickle cell trait. To me, this finding really underscores the potential clinical impact that the observed underestimation of A1C in those with sickle cell trait could have.

MedicalResearch.com: What should readers take away from your report?

Response: About 1 in 12 African Americans has sickle cell trait and most don’t know their status. For African Americans who are at-risk for developing diabetes or who have diabetes, interpret A1C values with caution. Talk to your doctor about your results. It may be helpful to have your doctor assess your risk using both A1C and glucose measures.

MedicalResearch.com: Is there anything else you would like to add?

Response: These findings were based on one method of A1C measurement. While it is an assay that is approved for use in those with sickle cell trait, we are unable to say whether our findings are due to assay interference or a biological phenomenon in those with sickle cell trait.

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Lacy ME, Wellenius GA, Sumner AE, Correa A, Carnethon MR, Liem RI, Wilson JG, Sacks DB, Jacobs DR, Carson AP, Luo X, Gjelsvik A, Reiner AP, Naik RP, Liu S, Musani SK, Eaton CB, Wu W. Association of Sickle Cell Trait With Hemoglobin A1c in African Americans. JAMA. 2017;317(5):507-515. doi:10.1001/jama.2016.21035

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on February 7, 2017 by Marie Benz MD FAAD