From the Guidelines
HbA1c is not a reliable marker for monitoring glycemic control in patients with sickle cell anemia due to the abnormal hemoglobin and shorter red blood cell lifespans associated with the disease. This is because HbA1c measures the percentage of hemoglobin that is glycated, but patients with sickle cell anemia have abnormal hemoglobin (HbS) and typically shorter red blood cell lifespans due to hemolysis, as noted in studies such as 1 and 1. The reduced red cell survival time leads to falsely low HbA1c values that do not accurately reflect average blood glucose levels.
Key Considerations
- Patients with sickle cell anemia have a chronic hemolytic anemia, painful vaso-occlusive crises, and acute and chronic end-organ damage, as described in 1 and 1.
- The use of HbA1c in these patients may lead to underestimation of the true average glucose level, which can have significant implications for diabetes management and patient outcomes.
- Alternative methods, such as fructosamine or glycated albumin, which measure protein glycation independent of red blood cell lifespan, may be more suitable for monitoring glycemic control in patients with sickle cell anemia.
Recommendations
- Clinicians should interpret any HbA1c results in sickle cell patients with caution and consider using alternative methods for monitoring glycemic control.
- Regular blood glucose monitoring and alternative tests, such as fructosamine or glycated albumin, should be used instead of relying on HbA1c values for diabetes management in patients with sickle cell anemia.
- Continuous glucose monitoring may also be a useful tool for monitoring glycemic control in these patients, as it can provide a more accurate picture of glucose levels over time.
From the Research
Significance of Hemoglobin A1c (HbA1c) in Patients with Sickle Cell Anemia
- HbA1c is unreliable in patients with sickle cell disease (SCD) and diabetes mellitus (DM) due to the shortened red cell lifespan 2, 3, 4
- The American Diabetes Association recommends monitoring long-term glycemia by measuring serum glucose, rather than relying on HbA1c 2
- Serum fructosamine has been proposed as an alternative marker for monitoring glycemic control in patients with SCD, as it is independent of red cell lifespan 2, 3, 5, 4
- Studies have shown that serum fructosamine is highly correlated with both HbA1c and fasting glucose, and can be used to identify individuals with uncontrolled glycemia and type 2 diabetes 3, 5, 4
Limitations of HbA1c in Sickle Cell Anemia
- Blood transfusions, a common treatment for SCD, can impact HbA1c levels, making them less reliable 2
- HbA1c may not accurately reflect glycemic control in patients with SCD, particularly those with hemoglobinopathies 3, 4
- Fructosamine has been shown to be a more reliable marker of glycemic control in patients with SCD, even in the presence of moderate hyperbilirubinemia 5