Laboratory medicine in primary care Glycated haemoglobin (HbA1c) monitoring
Glycation of haemoglobin to produce HbA1c occurs throughout the 120 day average lifespan of the red blood cell. Repeat testing in fewer than 120 days or situations that shorten this lifespan will produce HbA1c results that do not fully reflect current diabetic control. Timothy M Reynolds and colleagues discuss
This article describes two common scenarios involving the use of glycated haemoglobin (HbA1c) that may be seen in primary care and considers their potential clinical implications in monitoring patients with diabetes.
HbA1c has become established as the monitoring test of choice to assess medium term diabetic control and as a key parameter on which to base changes in management of patients. Common situations exist, however, in which the HbA1c can be misleading. As the average lifespan of a red blood cell is approximately 120 days, in situations in which red cell lifespan is reduced HbA1c may not accurately reflect diabetic control. With increasing emphasis on achieving lower HbA1c values in patients with diabetes, clinicians need to be aware of these situations and understand the limitations of the test methods used.
A 60 year old woman was seen for review of her diet controlled type 2 diabetes. She was taking long