From the Guidelines
False low A1C readings can occur due to several factors, including conditions that shorten red blood cell lifespan, such as hemolytic anemia, and should be interpreted with caution, considering alternative monitoring methods like fructosamine or glycated albumin tests, as recommended by the most recent guidelines 1. When interpreting A1C results, it's essential to consider various factors that can affect their accuracy. Conditions that shorten red blood cell lifespan, such as:
- Hemolytic anemia
- Blood loss
- Hemoglobinopathies like sickle cell disease can cause falsely low A1C results because there are fewer older red blood cells available for glucose attachment. Certain medications, including high-dose aspirin, vitamin C supplements, and some HIV medications, can also interfere with the test. Additionally, liver or kidney disease may affect A1C accuracy, as can recent blood transfusions, which introduce donor cells with different glucose exposure histories. Iron deficiency anemia, on the other hand, paradoxically causes falsely elevated (not lowered) A1C, as noted in previous studies 1. If a false low A1C is suspected, healthcare providers should compare the result with other glucose measurements, such as fasting blood glucose or glucose tolerance tests. Alternative monitoring methods, like fructosamine or glycated albumin tests, might be recommended for people with conditions that make A1C unreliable, as suggested by recent guidelines 1. It's crucial to discuss any discrepancies between A1C results and typical blood glucose readings with a healthcare provider to ensure proper diabetes management. The most recent guidelines emphasize the importance of considering these factors when interpreting A1C results, highlighting the need for a comprehensive approach to diabetes monitoring 1.
From the Research
Causes of False Low A1C
- Hemoglobinopathy, such as sickle cell disease plus beta-thalassemia, can cause falsely low levels of HbA1c 2
- Certain medications, like dapsone, can induce hemolysis, leading to a falsely low HbA1c level 3
- Conditions that affect erythrocyte count and reticulocyte count can also impact HbA1c results 3
Alternative Measures of Glycemic Control
- Fructosamine is a suitable alternative to HbA1c for monitoring long-term glycemic control in patients with type 2 diabetes mellitus and sickle cell disease 2, 4
- Fructosamine reflects mean blood glucose over a shorter period (three weeks) compared to HbA1c (three months) 5
- Glycated albumin is another alternative marker that reflects mean blood glucose over three weeks 5
Clinical Considerations
- Clinical laboratories should have a standard protocol to troubleshoot discrepant HbA1c results 3
- Healthcare providers should be aware of medications and conditions that may lead to falsely low HbA1c levels to avoid incorrect treatment decisions 3
- The relationship between HbA1c and fructosamine can be useful in monitoring long-term glycemic control in patients with sickle cell disease on chronic transfusion therapy 6