Clinical background:
HbA1c is a modified haemoglobin where a glucose is attached to the N-terminal valine of the beta chain of adult haemoglobin.
HbA1c measurement has two roles. The primary role is in the monitoring of glucose control in individuals with diabetes. More recently, under certain limitations, HbA1c has also been approved for use in the diagnosis of type 2 diabetes by the WHO.
HbA1c reflects glucose control over the lifespan of the red blood cell which is approximately 120 days.
The use of HbA1c is limited to patients that have a normal red cell lifespan and that have only normal adult haemoglobin (HbA0) present, though it may be possible to provide HbA1c for monitoring purposes in individuals with certain haemoglobinopathy traits such as HbS and HbC trait.
Specimen container paediatric:
EDTA whole blood
Specimen container adult:
EDTA whole blood
Minimum volume paediatric:
1 mL blood
Minimum volume adult:
1 mL blood
Special requirements:
Patient must be over 1 year of age
Sample stability:
2 days at 15 to 25°C,
7 days at 2 to 4°C
Reference ranges:
Non-diabetic: less than 42mmol/mol (IFCC)
Inadequate control: greater than 58mmol/mol (IFCC)
Diagnostic of diabetes: greater than 47mmol/mol (IFCC) **
** WHO guidance (2011) should be referred to for diagnostic limitations
Other info:
Fluoride oxalate and lithium heparin whole blood samples also acceptable