What HbA1c measures
Sugar in your blood sticks to haemoglobin, the oxygen-carrying protein in red blood cells. Red blood cells live for about three months, so the share of haemoglobin with sugar attached – your HbA1c – gives an average picture of blood sugar over that period.
That makes it different from a glucose reading, which is a snapshot of a single moment.
Why it matters for longevity
Blood sugar control is a core part of metabolic health, and HbA1c is one of the most widely used ways to track it over time. Higher HbA1c over many years is associated with damage to blood vessels, nerves, kidneys and eyes.
For proactive testers, the value is usually in the trend. A result that creeps up across several tests is worth discussing with a doctor, even if each result sits inside the lab's reference range.
How it's tested
- Sample
- Finger-prick or venous – widely available on home kits
- Fasting
- Not needed
- Units
- mmol/mol in the UK and most of Europe, % in the US
Before you test
- Changes take time to show, so re-testing sooner than about three months adds little.
- Tell the provider if you have anaemia or a known haemoglobin variant.
What can affect your result
- Anaemia, iron deficiency or recent blood loss
- Haemoglobin variants such as sickle cell trait
- Kidney or liver conditions
- Pregnancy
Talking to your doctor about your result
Your report will show your result next to the lab's reference range. Ranges differ between labs and units, and a result inside or outside the range isn't a diagnosis on its own. Share the full report with your doctor – especially if a result is flagged, you have symptoms, or there's a family history that concerns you. Don't start, stop or change any medicine or supplement based on a home test without medical advice.
What a HbA1c test costs
In our European price check (12 October 2026), the cheapest HbA1c test we found was €13 (Labor Dr. Heidrich (Hamburg), Germany); the cheapest option in the most expensive country was €70 (Netherlands). Lab prices often exclude a small blood-draw or visit fee. It can be better value as part of a panel if you want several of the core markers. See every price by country in our European blood test price guide.
HbA1c: common questions
What's the difference between HbA1c and fasting glucose?
Fasting glucose measures blood sugar at one moment after an overnight fast. HbA1c reflects the average over about three months. They answer different questions, and doctors sometimes look at both.
Do I need to fast for an HbA1c test?
No. HbA1c isn't affected by your last meal, which is one reason it suits home finger-prick kits.
How often is it worth re-testing HbA1c?
Because it averages roughly three months, re-testing more often than that rarely shows anything new. Many people include it in a yearly panel; agree the right interval with your doctor.
Related markers
Sources
[PLACEHOLDER: 2–4 primary references (guidelines, consensus statements) confirmed by the medical reviewer]