From the Guidelines
Hemoglobin A1c (HbA1c) measurements should be interpreted with caution in patients with anemia or renal failure, and alternative methods such as fructosamine, glycated albumin, continuous glucose monitoring, or self-monitoring of blood glucose may be necessary to accurately assess glycemic control. In patients with anemia, HbA1c may be falsely elevated in iron deficiency anemia and falsely decreased in hemolytic anemia or conditions with shortened red blood cell lifespan 1. For patients with renal failure, HbA1c tends to underestimate glycemic control due to reduced red blood cell survival, increased blood urea nitrogen affecting hemoglobin, and the impact of erythropoietin therapy 1.
Some key points to consider when interpreting HbA1c in patients with anemia or renal failure include:
- The severity of kidney disease, with more advanced disease potentially requiring less stringent HbA1c targets 1
- The presence of macrovascular complications, comorbidity burden, life expectancy, hypoglycemia risk, and patient motivation/preference for treatment intensity/support 1
- The potential for HbA1c to be decreased by factors that reduce erythrocyte life span, such as anemia, blood transfusion, and erythrocyte-stimulating agents or iron replacement therapy 1
- The potential for HbA1c to be falsely increased by metabolic acidosis, carbamylation, and advanced glycation end-product formation in later stages of diabetic kidney disease 1
In general, an individualized HbA1c target ranging from <6.5% to <8.0% is recommended for patients with diabetes and chronic kidney disease (CKD) not treated with dialysis 1. However, this target may need to be adjusted based on the patient's clinical condition, including the severity of anemia or renal impairment, recent blood transfusions, and erythropoietin therapy. Continuous glucose monitoring or self-monitoring of blood glucose may be particularly useful in patients with CKD, especially those with advanced disease or those undergoing dialysis, to inform daily treatment decisions 1.
From the Research
Hemoglobin A1c in Anemia and Renal Failure
- Hemoglobin A1c (HbA1c) is a widely used parameter for assessing long-term glucose control in diabetic patients 2.
- However, its reliability can be affected by factors such as anemia and renal failure, which can alter erythrocyte turnover and hemoglobin metabolism 3, 4.
- Studies have shown that HbA1c levels can be influenced by erythropoiesis-stimulating agent (ESA) therapy, which is commonly used to treat anemia in patients with chronic kidney disease (CKD) 2, 5.
- The correlation between HbA1c and fasting glucose can be weakened in patients with CKD, particularly those with anemia, making HbA1c a less reliable indicator of glycemic control in these patients 4.
- Alternative markers of glycaemia, such as glycated albumin and fructosamine, may provide additional information or a more reliable measure of glucose control in patients with CKD or anemia 3, 5, 6.
- These alternative markers can reflect glucose exposure over a shorter period than HbA1c and may be beneficial for monitoring rapid metabolic changes or changes in diabetes treatment 6.