HbA1c & blood glucose control

The bloodstream contains red blood cells. These special cells carry oxygen around the blood using a protein called haemoglobin. Glucose can also stick to this protein. When it does, it is called ‘glycated haemoglobin’ (HbA1c).

Red blood cells normally live for 8-12 weeks before they are replaced by new ones. Because of this, measuring HbA1c allows you and your doctor to see how good your blood sugar levels have been controlled over that 8–12-week period.

The higher the levels of glucose have been in your blood, the more HbA1c will be present.

HbA1c levels are usually below 42 mmol/mol (6%) in people who do not have diabetes.

HbA1c levels are usual 48 mmol/mol (6.5%) or above in people with diabetes.

Blood samples for testing HbA1c are most often taken from your arm with a needle.

HbA1c readings are different to the finger prick tests you may take. Finger prick tests are there to show you what your blood glucose level is at the very moment of the test.

You may also do what is called a fasting blood glucose test. This is to show you what your blood glucose levels are like when you have not had anything to eat for 8-10 hours. This test can be done using blood taken from a finger prick. It can also be done using blood taken from the arm.