HbA1C not enough to monitor diabetes in patients of African descent: Study

Current glycated haemoglobin A1c (HbA1c) cutoffs (HbA1c 5.7% to less than 6.5% for prediabetes; HbA1c of 6.5% or higher for type 2 diabetes), determined from predominantly White population cohorts, may perform suboptimally in evaluating glycemic status in this diverse population of African American, Afro-Caribbean, and African populations. To ensure accurate detection of type 2 diabetes, there is a need to understand the ability of HbA1c to correctly classify type 2 diabetes status and to evaluate interethnic variation among African American, Afro-Caribbean, and African people. Therefore, Dr Margrethe F. Horlyck-Romanovsky, PhD and her team conducted a study to assess glycemic status among African American, Afro-Caribbean, and African people.

In this systemic review study, researchers identified 3,238 articles published from PubMed, Scopus, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). After review of titles, abstracts, and full texts they included 12 articles for their analysis. They compare the HbA1c results with other ethnic groups and further validated them against the oral glucose tolerance test (OGTT), fasting plasma glucose (FPG), or previous diagnosis. They also classified study results by the risk of false positives and risk of false negatives in assessing glycemic status.

Key findings of the study were:

• Upon analyzing 5 studies of African American people, the researchers found that the HbA1c test increased the risk of false positives compared with White populations, regardless of glycemic status.
• From the results of the three studies on African Americans, they found that HbA1c of 5.7% to less than 6.5% or HbA1c of 6.5% or higher generally increased risk of overdiagnosis compared with OGTT or previous diagnosis.
• In one study of Afro-Caribbean people, they noted that HbA1c of 6.5% or higher detected fewer type 2 diabetes cases because of a greater risk of false negatives.
• Compared with OGTT, HbA1c tests in 4 studies of Africans, they found that HbA1c of 5.7% to less than 6.5% or HbA1c of 6.5% or higher leads to underdiagnosis.

The authors concluded, "HbA1c criteria inadequately characterizes glycemic status among heterogeneous African descent populations. Research is needed to determine optimal HbA1c cutoffs or other test strategies that account for risk profiles unique to African American, Afro-Caribbean, and African people living in the United States."

For further information:

https://www.cdc.gov/pcd/issues/2021/20_0365.htm#