Most people are aware that type 1 diabetes (T1D) management involves closely monitoring blood glucose levels. But there’s another test you may have heard of: the haemoglobin A1c (HbA1c) test.
Here’s what you need to know about HbA1c and how it’s tested, as well as other important tests for people living with T1D.
What is HbA1c?
When you check your blood glucose level (BGL) with a blood glucose meter (finger pricks), continuous glucose monitor (CGM) or flash glucose monitor (flash GM), you’re measuring how many molecules (or mmol) of glucose are in your blood stream right then.
The glucose in your blood stream attaches itself to the haemoglobin part of your red blood cells – and that’s what’s called glycated haemoglobin, or HbA1c. If there’s a lot of glucose in your blood stream, this will result in a higher number of haemoglobin with glucose attached.
What is the HbA1c blood test?
As your blood cells (and therefore your haemoglobin) live for around 120 days, your HbA1c result looks at your overall blood glucose levels for the preceding two to three months.
The HbA1c test is a blood test, and your doctor or diabetes team might arrange for you to have it for a number of reasons, including:
- ongoing diabetes management. It’s important to schedule an HbA1c test at least twice a year, and perhaps more frequently if your results aren’t optimal, or if your medication or health conditions change. Chat with your doctor to figure out your ideal testing frequency.
- testing for prediabetes or diagnosis of diabetes. If you’re experiencing symptoms of type 1 or type 2 diabetes, your doctor might suggest an HbA1c test to confirm a diagnosis.
- during pregnancy. HbA1c tests are increasingly being used to monitor for gestational diabetes and to detect elevated HbA1c in pregnant people living with type 1 diabetes, which is associated with maternal-foetal complications.
HbA1c measurements can be reported as percentages (HbA1c as a percentage of total haemoglobin) or the scientific unit of mmol/mol (millimoles HbA1c per mole of total haemoglobin). Medicare offers a subsidy, allowing you to have the test up to four times within a year.
HbA1c and diabetes diagnosis
The HbA1c test is one of the most comprehensive tests available for type 1 diabetes diagnosis.
When it comes to diagnosing diabetes, healthcare experts recommend using an HbA1c level of 6.5% (7.8mmol/L) as the target. However, it’s important to note that having a value below 6.5% doesn’t necessarily rule out diabetes that was diagnosed using glucose tests. It’s always best to consult with your doctor for a comprehensive understanding of your specific situation.
Read about other tests for diagnosing type 1 diabetes.
What is a normal HbA1c level?
When it comes to HbA1c levels:
- below 5.7% (39mmol/mol) is considered normal
- a range of 5.7% (39mmol/mol) to 6.4% (46mmol/mol) indicates prediabetes
- a value of 6.5% (48mmol/L) or higher suggests diabetes.
If your HbA1c falls within the prediabetes range, remember that the higher it is, the greater your risk of developing type 2 diabetes.
What HbA1c result should I aim for?
It’s recommended that adults living with type 1 diabetes aim to keep their HbA1c as close to 53mmol/mol (or 7%) as possible, as long as this can be achieved without significant episodes of hypoglycaemia.
Research has shown that keeping your HbA1c near this goal can significantly reduce your risk of developing the long-term complications of diabetes. In a study, researchers found that individuals with an HbA1c level of 7% or higher had a higher risk of developing retinopathy and early kidney disease compared to those with levels between 6.5% and 6.9%. The risk escalated for those with an HbA1c of 8.6% or higher.
Over time, your targets may need to change, so make sure you discuss what your target should be with your diabetes team.