Hemoglobin test results differ in African Americans with sickle cell

Accurate results on A_1c blood sugar tests are crucial for patients to monitor and treat themselves accordingly. Researchers, whose work was published Feb 7, 2017, in the Journal of the American Medical Association, examined data from two large studies to determine if a difference in A_1c levels in African American patients with sickle cell trait.

Researchers evaluated African Americans with and without sickle cell trait to determine if there is a significant difference in A_1c levels. The study included a total of 4,620 patients, 367 of whom had sickle cell trait, and examined levels of A_1c levels of fasting or two-hour glucose levels.

“Although data are limited, it is hypothesized that the presence of sickle hemoglobin results in a shorter lifespan for red blood cells,” wrote Mary E. Lacy, MPH, first author on the study, and colleagues. “This would result in less available time for hemoglobin glycation, which in turn may influence the interpretation of HbA_1c in relationship to the glucose values they intend to represent. Correct interpretation of HbA_1c values in individuals with SCT is important because it directly affects efforts that use HbA_1c for screening, diagnosis, and monitoring of diabetes and prediabetes.

Results showed that A_1c levels were significantly lower in those with sickle cell trait (5.72 percent) than in patients without (6.01 percent). This change in glucose levels could potentially endanger patients with sickle cell trait in that they do not receive the correct information in how to treat their disease.

“Our results suggest that currently accepted clinical measures of HbA_1c do not reflect recent past glycemia in the same way in African Americans with and without sickle cell trait as evidenced by significantly lower HbA_1c values at the same glucose concentration in those with versus without SCT,” wrote Lacy and colleagues. “These results could have clinically significant implications. The possibility of benefit from incorporating information on hemoglobin variants into clinical guidelines for interpreting HbA_1c values for screening and diagnosis of prediabetes and diabetes. Because black people typically have a higher prevalence of diabetes and experience a number of diabetic complications at higher rates than white people, the cost of inaccurately assessing risk and treatment response is high.”