This article was last reviewed on
This article waslast modified on 10 July 2017.

Haemoglobin A1c (HbA1c) is made when glucose attaches itself to haemoglobin in red blood cells. The level of HbA1c indicates the average blood glucose level during the previous two or three months. The higher the blood glucose the higher the HbA1c. To help guide treatment, the NHS now expects diabetics to have HbA1c measurements at least twice a year.

In 2007, a new worldwide standard for HbA1c measurement was adopted and shortly the NHS will change the way it is reports this important lab test. Instead of using the percentage of HbA1c in total haemoglobin, the NHS will use the ratio of HbA1c to haemoglobin which is not attached to glucose and will have the measurement units ‘mmol/mol’. These changes greatly alter the number reported by the laboratory. For example, an HbA1c of 7.5% becomes 59 mmol/mol.

The benefit of the change is that the HbA1c results obtained by labs throughout the world should now be the same. In the UK, NHS labs will report results both ways between 1 June 2009 and 1 June 2011 - that should be long enough for everyone to become familiar with the new lab reports!