From the Guidelines
Anemia can significantly impact HbA1c results, with iron deficiency anemia potentially leading to falsely elevated levels and hemolytic anemia resulting in falsely lowered levels, as evidenced by recent studies 1.
Key Considerations
- The effect of anemia on HbA1c levels depends on the type of anemia, with iron deficiency anemia prolonging red blood cell lifespan and increasing glycation rates, thus potentially elevating HbA1c levels 1.
- Conversely, conditions with increased red blood cell turnover, such as hemolytic anemia, can lead to falsely lowered HbA1c levels due to the reduced time available for glycation 1.
- For patients with known anemia, alternative methods of glucose monitoring, such as fructosamine testing or glycated albumin measurement, should be considered to accurately assess glycemic control 1.
Clinical Implications
- Healthcare providers should interpret HbA1c results with caution in anemic patients, taking into account the complete clinical picture, including hemoglobin levels, red blood cell indices, and iron studies 1.
- The use of HbA1c as a diagnostic tool for diabetes may be limited in patients with certain types of anemia, and other diagnostic criteria, such as fasting plasma glucose or oral glucose tolerance test, may be necessary 1.
- Recent studies have highlighted the importance of considering the impact of anemia on HbA1c results, particularly in patients with advanced chronic kidney disease, where HbA1c may be falsely low due to anaemia, use of erythropoietin-stimulating agents, or reduced erythrocyte lifespan 1.
From the Research
Effect of Anemia on HbA1c Levels
- Anemia can affect HbA1c levels, making it an inadequate diagnostic tool for diabetes mellitus in anemic subjects 2
- The prevalence of anemia can lead to a consequent alteration in the HbA1c value, irrespective of the circulating blood glucose concentration 3
- Different types of anemia, such as iron deficiency anemia and sickle cell anemia, can increase HbA1c levels in non-diabetic patients 4
Types of Anemia and Their Effects on HbA1c
- Iron deficiency anemia can increase HbA1c levels, which can be corrected with oral iron supplementation 4, 5
- Sickle cell anemia can also increase HbA1c levels, with lower hemoglobin and higher red cell distribution width correlating with higher HbA1c levels 4
- Megaloblastic anemia and beta-thalassemia trait do not significantly affect HbA1c levels 4
Clinical Implications
- Anemia should be corrected before setting the treatment goal of optimal HbA1c control, especially when the level is in the diagnostic threshold 5
- Fructosamine measurement can be used to confirm poorly-controlled diabetes in patients with anemia, as it is unaffected by disorders of red blood cells 6
- Caution is required when interpreting HbA1c levels in patients with anemia, and alternative diagnostic tools may be necessary 3, 2