Diagnostic Limitations of Hemoglobin A1c in the Setting of Compound Hemoglobinopathy: A Case Report of Sickle Cell Disease, Alpha Thalassemia, and Occult Diabetes

This case report illustrates the diagnostic limitations of hemoglobin A1c (HbA1c) in patients with coexisting hemoglobinopathies. Sickle cell disease (SCD) and alpha thalassemia are inherited disorders characterized by chronic anemia and altered red blood cell turnover, both of which can significantly interfere with the accuracy of HbA1c measurements. In such cases, HbA1c may appear falsely low, potentially delaying the diagnosis and treatment of diabetes mellitus. We describe a 63-year-old female with previously undiagnosed SCD and alpha thalassemia whose longstanding hyperglycemia and diabetic complications were masked by inappropriately low HbA1c values. This report emphasizes the importance of recognizing the limitations of HbA1c in vulnerable populations and highlights the need for alternative glycemic markers, such as fructosamine, in patients with hemoglobinopathies to ensure accurate diagnosis and monitoring of diabetes mellitus.