A1c stands for glycated hemoglobin, a molecule that forms when the oxygen transporting-protein hemoglobin naturally bonds with glucose in the blood.

This ‘glycated’ molecule is also commonly expressed as hemoglobin A1c, and measuring it gives clinicians a marker of your average blood sugar over the preceding 8 to 12 weeks.

How is A1c measured?

An A1c test is a clinical test that involves taking a sample of blood, often from the arm but sometimes from the finger, and using a specialist machine to measure the level of glycated hemoglobin.

Hemoglobin is a protein found within your red blood cells that helps to carry oxygen around the body.

In the presence of glucose, hemoglobin bonds to glucose so people with higher levels of glucose in the blood for extended periods of time will have higher levels of glycated hemoglobin until those red blood cells reach the end of their life, which typically takes 90 days.

The A1c test therefore gives a good indication of how high your blood glucose levels have been over the past 3 months.

When are A1c tests run?

A1c tests are run so you and your health team can monitor how well your diabetes is being controlled. Your doctor may give you your results as an A1c percentage or may give your results as estimated average glucose (eAG) which is given in mg/dL (milligrams per deciliter).

A1c tests may also be used in assessing risk of type 2 diabetes for people not diagnosed with diabetes.

Target A1c levels

Targets for A1c are as follows:

  • For people without diabetes, the range is 4 to 5.9% (eAG 68 to 123 mg/dL)
  • For non-pregnant adults with diabetes, an A1c level of 7% (eAG 154 mg/dL)  is considered good control, although some people that are not at risk of hypoglycemia may prefer their numbers to be closer to that of non-diabetics
  • For children with diabetes, a target A1c of 7.5% (eAG 169) is recommended
Indication A1c (%) eAG (mg/dL)
Non-diabetic 4.0 to 5.9 68 to 123
Target for non-pregnant adults with diabetes 7 or below 154 or below
Target for children with diabetes 7.5 or below 169 or below

Note that if you have an individual target set for you by your doctor, you should aim to stick to it.

If your A1c result is higher than your target, you and your health team should work together to help you to meet the target in future.

Research has also shown that people with type 2 diabetes who reduce their A1c level by 1% are:

  • 19% less likely to suffer cataracts
  • 16% less likely to suffer heart failure
  • 43% less likely to suffer amputation or death due to peripheral vascular disease

A1c targets and pregnancy

Women with diabetes planning a pregnancy should aim to achieve an A1c level of 7% (eAG 154 mg/dL) or under before becoming pregnant.

Diagnosis of type 2 diabetes

The A1c test can also be a useful tool in assessing risk and diagnosing type 2 diabetes, as shown below:

Indication Result (%)
Normal 4 to 5.9
Prediabetes 6.0 to 6.4
Type 2 diabetes 6.5 or above

A1c and risk of complications

Research shows that people who can maintain lower A1c levels have a significantly lower risk of developing long term diabetes complications than people with higher A1c levels.

If you are diagnosed with diabetes, it’s recommended you try to reduce your A1c as best you can. If you are on insulin, sulfonylureas or glinide medication, however, you will need to do this in a way that does not significantly raise the risk of hypoglycemia.