Calculators and Tools

HbA1c Units Converter – DCCT to IFCC

Since June 2011, the way HbA1c values are reported has switched from a percentage to a measurement in mmols/mol. To make sense of the new units and compare these with old units and vice versa, use our HbA1c units converter.

Why did HbA1c units change?

The old, percentage way of reporting HbA1c values is known as the DCCT (Diabetes Control and Complications Trial) units.

The new mmols/mol values are known as the IFCC (International Federation of Clinical Chemistry) units.

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European countries have been using the IFCC units for a number of years and usage of the IFCC units by the UK will allow easier comparisons to be made between UK and European results.

Haemoglobin molecules stay in the blood for around 3 months so the HbA1c test is able to give a measure of how glucose has interacted within our blood over up to a 3 month period.

Getting familiar with the HbA1c unit changes

Download a free chart which converts HbA1c in % units to mmol/mol and vice versa.

Are the new HbA1c units related to blood glucose test units?

The new HbA1c units (mmol/mol) looks similar to the units used for blood glucose tests (mmol/l) but they are measuring two different values.

The HbA1c test measures how much haemoglobin in the blood has become glycated (chemically bonded with glucose).


HbA1c is a measure of how well controlled your blood sugar has been over a period of about 3 months. It essentially gives a good idea how high or low, on average, your blood glucose levels have been.

A sample of blood will be take, usually from your arm. The test measures how much glucose has stuck to haemoglobin in the blood.

Download a FREE HbA1c to mmol/L chart for your phone, desktop or as a printout.
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How does HbA1c differ to a blood glucose test?

Blood glucose tests, by comparison, measure the concentration of glucose molecules present in the blood at the very time of the test.

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