Pitfalls of using HbA1c in the diagnosis and monitoring of diabetes

Question What are the pitfalls of using glycated haemoglobin (HbA1c) in the diagnosis and/or monitoring of diabetes?Background HbA1c has become ubiquitous in its use for the diagnosis of diabetes. It is dependent on the glycation of red blood cells over time. Several variables can affect the HbA1c value, leading to a false-positive or false-negative result, which can significantly affect clinical management. Therefore, it is important that clinicians are aware of alternative tests with which to diagnose and monitor diabetes.Setting This is a case study of a patient with sickle cell trait, whose diagnosis of diabetes mellitus was delayed due to a low HbA1c value on laboratory testing. The patient was subsequently diagnosed as having diabetes by capillary blood glucose and the use of the fructosamine assay.Discussion There are several medical conditions that can affect the HbA1c value, including haemoglobinopathies. Awareness of alternate ways of diagnosing and monitoring diabetes is therefore important for...