From the Guidelines
A1C testing is less accurate in individuals with beta thalassemia trait and should not be relied upon for diabetes diagnosis or monitoring in these patients. The presence of beta thalassemia trait typically causes falsely low A1C results that underestimate actual blood glucose levels, potentially leading to missed or delayed diabetes diagnoses. This inaccuracy occurs because beta thalassemia trait affects hemoglobin structure and red blood cell lifespan, which are fundamental to how A1C measures glycemic control 1. For patients with beta thalassemia trait, alternative methods such as:
- Fasting plasma glucose tests
- Oral glucose tolerance tests
- Fructosamine testing
- Glycated albumin measurements provide more reliable assessments of glycemic control. Continuous glucose monitoring may also be beneficial for real-time glucose tracking. Patients with beta thalassemia trait should inform all healthcare providers about their condition to ensure appropriate testing methods are used for diabetes screening and management. It is essential to consider the limitations of A1C testing in individuals with beta thalassemia trait, as highlighted in recent guidelines 1, to prevent potential misdiagnosis or delayed diagnosis of diabetes.
From the Research
Accuracy of HbA1C in Diagnosing Diabetes
- The accuracy of Hemoglobin A1C (HbA1C) in diagnosing diabetes in individuals with beta thalassemia trait is affected by the presence of hemoglobin variants 2, 3.
- Studies have shown that HbA1C levels may be misleading in patients with beta thalassemia trait due to the shortened red blood cell lifespan and increased erythrocyte turnover 4.
- HbA1C may not be a reliable marker for diagnosing diabetes in individuals with beta thalassemia trait, especially in those with marked erythrocyte turnover 4.
- Fructosamine has been proposed as an alternative marker for glucose control in patients with beta thalassemia trait, as it is less affected by hemoglobin variants and red blood cell lifespan 4, 5.
Factors Affecting HbA1C Measurements
- Hemoglobin variants, such as beta thalassemia trait, can cause errors in HbA1C determination using certain measurement systems 3.
- The presence of hemoglobin E (HbE) can also complicate HbA1C measurements, especially in patients with homozygous HbE 2, 3.
- The choice of measurement system can affect the accuracy of HbA1C results, with some systems being more prone to errors in the presence of hemoglobin variants 3.
Clinical Implications
- Clinicians should be aware of the potential limitations of HbA1C in diagnosing diabetes in individuals with beta thalassemia trait and consider alternative markers, such as fructosamine 5, 4.
- Hemoglobin typing should be considered as basic information prior to HbA1C measurement, especially in populations with a high prevalence of hemoglobinopathies 2.