Keywords: Haemoglobin A1c, Glycated Hb, GHB, Glycosylated haemoglobin, Glycohaemoglobin


5 mL blood in lithium heparin tube.


Chromatography, electrophoresis, immunoassay.

Methods may be specific for HbA1c or may measure total glycohaemoglobin (HbA1).

Reference Interval:

HbA1c: 3.5 - 6.0% (15-42 mmol/mol)

HbA1c: 6.1 - 6.4% (43-47 mmol/mol) indeterminate

HbA1c: ≥ 6.5% (≥48 mmol/mol) diagnostic of diabetes.


Diabetes mellitus: monitoring of glycaemia over previous three months. Diagnosis of diabetes.


The result reflects the average glucose concentration over the life of the red cells although some methods give a falsely high reading if the patient is hyperglycaemic when the blood is collected.

HbA1c levels < 8% indicate good control.

Levels will be lower than appropriate for the degree of diabetic control in the presence of a reticulocytosis.

See also Fructosamine.

Krishnamurti U and Steffes MW. Clin Chem 2001; 47: 1157-65.
d'Emden MC et al. MJA 2012; 197: 220-222.

d'Emden MC et alMJA 2015; 203: 89-91. https://www.rcpa.edu.au/getattachment/cd22803f-1005-4712-a958-13ca6335f6c8/Guidance-concerning-the-use-of-glycated-haemoglobi.aspx