Markedly Low Hemoglobin A1c in a Patient with an Unusual Presentation of ß-Thalassemia Minor

ObjectiveTo describe very low hemoglobin A_1c levels in a patient with type 2 diabetes mellitus and an unusual presentation of β-thalassemia minor.MethodsWe present the clinical and laboratory findings of the study patient.ResultsA 64-year-old African American man with type 2 diabetes mellitus was referred to the endocrinology clinic with a hemoglobin A_1c level of 1.6% despite elevated blood glucose concentrations. A red blood cell survival study with chromium-51 revealed that he had a reduced erythrocyte life span less than 25% of normal. He also had a markedly elevated reticulocyte count ranging from 236 to 534 x 10³/μL (reference range, 25-75 x 103/μL). The laboratory findings, which are not characteristic of ß-thalassemia minor, could be the cause of the markedly low hemoglobin A_1c in this patient.ConclusionsAlthough rare, when associated with marked erythrocyte turnover, β-thalassemia minor can lead to a severe reduction in HbA_1c levels. In this scenario, glycemic control is best assessed by measuring fructosamine. (Endocr Pract. 2010;16:89-92)