HbA1c Test

The test for HbA1c shows how well you have controlled your diabetes over the last few months. Even though you may have some very high or very low blood glucose values, HbA1c will give you a picture of the average amount of glucose in your blood over that time period. The result can help you and your doctor understand if the measures you are taking to control your diabetes are working.

The Department of Health recommends that everyone with diabetes has HbA1c measured at least twice a year. HbA1c may be measured more frequently in those who have just been diagnosed with diabetes, in those whose blood glucose remains too high, or when a treatment plan changes.

If you have diabetes and your HbA1c is below the target of 6.5% of the total amount of haemoglobin in the blood it is likely that your diabetes is in good control. If your HbA1c rises above 6.5%, you are at increased risk of developing long term complications such as eye disease, kidney disease or nerve damage.

Since 1st June 2009 the way HbA1c results are reported in the UK has changed to help standardise measurements. The new units are mmol of HbA1c per mol of haemoglobin.  The recommended target of 6.5% now corresponds to a value of 48 mmol/mol. Until June 2011 results will be reported both as a percentage and as mmol/mol to help everyone become familiar with the new units. More information about the new way of reporting test results can be found here.

If you have an abnormal type of haemoglobin, for example if you suffer from sickle cell disease, accurate results will depend on the method used to measure your HbA1c. If you have haemolysis or heavy bleeding, your test results may be falsely low. Finally, if you are iron deficient, this may raise your HbA1c measurement.