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Lower HbA1c levels linked to sickle cell trait in black adults
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Black adults with sickle cell trait have lower HbA1c values compared with participants without sickle cell trait despite similar fasting and 2-hour glucose levels, according to findings published in JAMA.
“About one in 12 African Americans has sickle cell trait and most don’t know their status,” Mary E. Lacy, MPH, a doctoral candidate in the department of epidemiology at Brown University School of Public Health, told Endocrine Today. “When seeing an African American patient who is at risk for developing diabetes or who has diabetes, it may be wise to use a more comprehensive approach to assessing glycemic control (ie, using HbA1c and fasting or 2-hour glucose). Our findings were based on an HbA1c assay that is approved for use in patients with sickle cell trait but because HbA1c was only measured using one assay we cannot say whether these findings would be replicated when using a different method of HbA1c measurement.”
Lacy and colleagues evaluated data from the Coronary Artery Risk Development in Young Adults (CARDIA) study and the Jackson Heart study on 4,620 black adults (mean age, 52.3 years; 61.3% women; 7.9% with sickle cell trait) to determine the association between HbA1c and sickle cell trait.
Mean fasting and 2-hour glucose values were similar between participants with and without sickle cell trait, whereas mean HbA1c was lower in participants with sickle cell trait (5.7%) compared with those without it (6%). Mean HbA1c values also were lower in participants with sickle cell trait for a given 2-hour glucose level (5.35%) compared with participants without it (5.65%; P < .001).
Researchers also evaluated a subset of the participants without a previous diagnosis of diabetes and who were not using diabetes medications and found that the prevalence of prediabetes was not significantly different in participants with and without sickle cell trait when fasting glucose and 2-hour glucose values were used. However, when HbA1c values were used to define prediabetes and diabetes, the prevalence was lower among participants with sickle cell trait compared with participants without it (P < .001 for all).
“Because there is often a long asymptomatic phase before diagnosis of type 2 diabetes and there are effective interventions that can delay or prevent progression from prediabetes to diabetes, early detection through screening is especially important,” Lacy told Endocrine Today. “In a routine clinical setting, a difference of 0.3 percentage points in HbA1c could be the difference between being identified as high-risk, and being targeted for more frequent monitoring as well as additional diabetes prevention efforts, or not, or receiving a diagnosis of diabetes or not. One point to remember is that the difference of 0.3 percentage points in HbA1c was an average across all available glucose values. This difference was smaller at lower glucose values and larger at higher glucose values. This means that the HbA1c difference may be more clinically meaningful in terms of managing glycemic control in those with known diabetes.” – by Amber Cox
For more information:
Mary E. Lacy, MPH, can be reached at mary_lacy@brown.edu.
Disclosure: The researchers report no relevant financial disclosures.
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