HbA1c Test in Australia

What an HbA1c test is

HbA1c, or glycated haemoglobin, is the fraction of haemoglobin in your red cells that has glucose irreversibly attached to it, expressed in Australia as millimoles per mole of total haemoglobin.

Glucose in the bloodstream binds slowly and non-enzymatically to haemoglobin inside red cells. The higher the average glucose concentration and the longer the exposure, the greater the proportion of haemoglobin that ends up glycated. Because red cells live roughly 120 days, the measurement integrates glucose exposure over the preceding two to three months, weighted towards the most recent four to six weeks.

That averaging property is what makes HbA1c useful. A fasting glucose is a single instantaneous snapshot that moves with what you ate yesterday, how you slept and whether you are unwell. HbA1c cannot be gamed by fasting for a day, and it needs no preparation at all.

Australia reports HbA1c primarily in IFCC units (mmol/mol), with the older DCCT/NGSP percentage alongside, because both remain in circulation. The two are directly convertible: 42 mmol/mol equals 6.0%, 48 mmol/mol equals 6.5%, 53 mmol/mol equals 7.0%.

Since 2014, an HbA1c performed in an accredited Australian laboratory has been Medicare-rebatable for diagnosing diabetes in asymptomatic at-risk adults, and it is the test most Australian GPs now use for both diagnosis and monitoring.

Why HbA1c is measured

HbA1c is used to diagnose type 2 diabetes, to identify people at high risk before diabetes develops, and to monitor glycaemic control in people already diagnosed.

Type 2 diabetes develops silently. Australians commonly live with elevated glucose for years before symptoms appear, and by the time thirst, frequent urination or blurred vision are noticeable, damage to small blood vessels may already have begun. A single HbA1c identifies that state without symptoms and without fasting.

The intermediate zone matters just as much. An HbA1c of 42–47 mmol/mol (6.0–6.4%) is not diabetes, but it marks substantially raised risk of progressing to it — a group where structured lifestyle change through programs such as those offered by Diabetes Australia demonstrably reduces progression.

For people already diagnosed, HbA1c is the standard monitoring test, typically repeated every three to six months. Targets are individualised by a doctor: a general target around 53 mmol/mol (7.0%) is common, but appropriate targets differ with age, duration of diabetes, medicines used and hypoglycaemia risk.

• Family history of type 2 diabetes, or a personal history of gestational diabetes.
• Overweight or obesity, particularly central adiposity.
• High blood pressure, abnormal lipids or polycystic ovary syndrome.
• Aboriginal and Torres Strait Islander, Pacific Islander, South Asian, Chinese or Middle Eastern ancestry, where risk is higher at younger ages.
• Symptoms such as thirst, frequent urination, fatigue, recurrent infections or slow-healing wounds — see your GP promptly for these.

What a high result can indicate

A raised HbA1c indicates that average blood glucose has been elevated over recent months, and at 48 mmol/mol (6.5%) or above it meets the Australian laboratory threshold for diagnosing diabetes.

Diagnosis is not made on one number in isolation. Australian practice is that in an asymptomatic person a diagnostic HbA1c should be confirmed by a repeat test, and interpretation always sits with a doctor who can consider symptoms, other results and your history.

Results in the 42–47 mmol/mol (6.0–6.4%) band indicate high risk rather than disease. This is the range where GPs discuss diet, physical activity, weight and sleep, and where a structured Australian diabetes prevention program is often recommended.

Some elevations are artefactual. Iron deficiency anaemia can falsely raise HbA1c because older red cells persist longer. So can B12 deficiency, splenectomy and some haemoglobin variants, depending on the assay. This is a real reason to run an FBC and iron studies alongside HbA1c rather than reading it alone.

What a low result can indicate

A low HbA1c usually means normal glucose metabolism, but a result well below the reference range can reflect shortened red cell survival rather than low blood sugar.

Anything that shortens red cell lifespan gives glucose less time to attach and pushes HbA1c artificially down: haemolytic anaemia, recent significant blood loss, recent transfusion, pregnancy, advanced chronic kidney disease, and some haemoglobinopathies including thalassaemia trait — which is common in Australia.

In these situations HbA1c is unreliable and Australian guidance is to use alternatives such as fasting plasma glucose or an oral glucose tolerance test. Your GP decides which is appropriate.

A genuinely low HbA1c in someone taking glucose-lowering medicines can indicate frequent hypoglycaemia, which is a reason to review those medicines with the prescribing doctor.

Australian reference ranges and diagnostic thresholds

Australian laboratories report HbA1c in mmol/mol with the percentage equivalent, and apply the diagnostic threshold of 48 mmol/mol (6.5%) for diabetes on a laboratory-measured sample.

Who should consider an HbA1c test

HbA1c suits adults with any risk factor for type 2 diabetes, anyone tracking metabolic health, and people already diagnosed who are monitoring control.

HbA1c is not the right test for diagnosing diabetes in pregnancy, in children, or where type 1 diabetes is suspected — those need different testing arranged by a doctor, urgently in the case of suspected type 1.

• Adults aged 40 and over, or younger with a family history or higher-risk ancestry.
• Anyone with a previous high-risk HbA1c, or a history of gestational diabetes.
• People with high blood pressure, raised lipids, fatty liver or polycystic ovary syndrome.
• Anyone establishing a metabolic baseline alongside lipids, liver function and a full blood count.
• People with known diabetes monitoring control between GP reviews.

How testing works with FORM in Australia

You choose the test, we issue an Australian pathology request form, you walk in to an accredited collection centre at any time of day, and your result is returned in mmol/mol and % with a written explanation.

• No referral from your own GP is required. Privately requested pathology is arranged under a request from a registered medical practitioner working with our accredited lab partner.
• Collection is a walk-in at Laverty (Healius) pathology centres Australia-wide.
• No fasting and no timing requirement — HbA1c can be collected whenever suits you.
• Results typically report within one to two business days, in mmol/mol with the percentage equivalent.
• We recommend running a full blood count and iron studies alongside, because anaemia can distort HbA1c.
• FORM is a diagnostic testing service. We do not diagnose diabetes, prescribe or treat — any result at or above 42 mmol/mol should be taken to your GP.
• Australian ordering is currently pre-sale. Join the waitlist for launch notification.