HbA1c (glycated haemoglobin)

Your average blood sugar over roughly the last three months, in one number.

What it measures

The percentage of your haemoglobin (the oxygen-carrying protein in red blood cells) that has sugar stuck to it — which reflects average glucose over the ~3-month life of a red blood cell.

Why it matters

It smooths out day-to-day noise, so it’s a steadier read on metabolic health than a single glucose reading. Rising HbA1c within the “normal” range already tracks with higher long-term risk.

Healthy target

< 5.4 %

How to read your value

It lags real change by weeks, so a new diet won’t show up immediately. It can read falsely low or high with some anaemias and haemoglobin variants. One value is a snapshot, not a diagnosis of diabetes — that needs a clinician and usually repeat testing.

What can affect it

• Diet pattern, especially refined carbohydrate and sugar intake
• Body weight and physical activity
• Some anaemias and haemoglobin variants distort it
• Certain medications

Does the target differ by age or sex?

Same target for men and women. It reads slightly higher on average with age, and is distorted by some anaemias and haemoglobin variants (which vary by ancestry) — not by sex.

When to talk to a clinician

Have it interpreted by a clinician if it is above the non-diabetic range, and never start or stop diabetes medication based on a single number.