What is HbA1c?
Everything You Need to Know
Updated March 2026 · Validated by diabetes specialists · 5 min read
In brief:
HbA1c measures your average blood sugar over the past 2–3 months. It is the most important single measurement for assessing diabetes control. The lower the value (within a safe range), the lower the risk of complications.
What does HbA1c actually mean?
HbA1c stands for glycated haemoglobin. Haemoglobin is the protein in red blood cells that carries oxygen around the body. When blood sugar is high, sugar binds to the haemoglobin — and this can be measured.
Since red blood cells live for about 2–3 months, HbA1c gives an average picture of blood sugar over this period. That makes it far more useful than a single blood sugar measurement.
What are normal HbA1c values?
| HbA1c (mmol/mol) | HbA1c (%) | Assessment |
|---|---|---|
| Below 39 | Below 5.7% | ✅ Normal – no diabetes |
| 39–47 | 5.7–6.4% | ⚠️ Elevated – increased risk (prediabetes) |
| 48 and above | 6.5% and above | 🔴 Diabetes |
| Below 53 | Below 7.0% | 💚 Treatment target for most people with diabetes |
Important to know:
Your treatment target may vary. For older patients, those with frequent hypoglycaemia or other conditions, a doctor may recommend a higher target. Always talk to your diabetes care team about what is right for you.
How is HbA1c measured?
HbA1c is measured with a simple blood test — either from a vein or a fingertip prick. You do not need to fast before the test. The test is usually done at your GP or diabetes clinic.
Most people with diabetes are advised to have HbA1c checked every 3 months, especially if blood sugar is not well controlled. Once it is stable, it may be checked every 6 months.
Why is HbA1c so important?
High HbA1c over time increases the risk of serious complications:
- ●Kidney damage – diabetic nephropathy
- ●Eye damage – diabetic retinopathy (can cause blindness)
- ●Nerve damage – neuropathy (tingling and numbness)
- ●Heart and vascular disease – increased risk of heart attack and stroke
Studies show that lowering HbA1c by just 1% (11 mmol/mol) reduces the risk of complications by 20–40%. There is a lot to be gained.
How to improve your HbA1c value
1. Diet
Reduce fast carbohydrates (white bread, sugar, soft drinks) and choose wholegrains, vegetables and protein. Regular meals at consistent times help keep blood sugar stable.
2. Physical activity
Just 30 minutes of brisk walking daily can lower HbA1c by 0.5–1%. Muscles use blood sugar as energy — without requiring insulin.
3. Medication and insulin
Take medications as prescribed and don't skip doses. Talk to your doctor if you experience side effects — there are often alternatives.
4. Regular blood sugar monitoring
The better you understand your own patterns, the easier it is to adjust diet and activity. A continuous glucose monitor (CGM) can provide extra insight.
💚 A realistic goal
Most people can lower HbA1c by 1–2% (11–22 mmol/mol) within 3–6 months with lifestyle changes alone. Small, consistent changes have a greater effect than drastic short-term ones.
Common questions about HbA1c
Can HbA1c be inaccurate?
Yes, in some cases. Anaemia, kidney disease, blood transfusions and certain genetic variants of haemoglobin can affect the result. Your doctor will take this into account.
Is HbA1c the same as daily blood sugar?
No — they measure different things. Daily blood sugar (mmol/L) shows a snapshot, while HbA1c shows the average over months. Both are important.
What if HbA1c is below 39 but I have symptoms?
Contact your doctor. A normal HbA1c does not rule out other causes of symptoms such as fatigue, thirst or frequent urination.
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