What HbA1c actually measures
When glucose stays in your blood, some of it sticks permanently to the haemoglobin inside your red blood cells. This 'glycated haemoglobin' is what HbA1c measures — the percentage of your haemoglobin that's got sugar stuck to it.
Red blood cells live about 90–120 days. So HbA1c is essentially a moving average of your blood sugar over the last three months. High average sugar → more haemoglobin got stuck with glucose → higher HbA1c.
The numbers to know
Below 5.7% is normal — no diabetes.
5.7% to 6.4% is pre-diabetes — high enough to matter, low enough to potentially reverse with lifestyle changes.
6.5% or above (confirmed on two tests) is diabetes.
Once diagnosed, most guidelines suggest keeping HbA1c below 7%. Indian cardiologists often push for tighter — below 6.5% — because Indian patients develop complications faster than the international average.
Why your target may be different from your neighbour's
Your ideal HbA1c depends on your age, how long you've had diabetes, other health conditions, and your risk of severe low-sugar episodes.
A young, otherwise healthy person may aim for 6.5%. An 80-year-old with heart disease may aim for 7.5% because pushing lower risks dangerous hypoglycaemia. Pregnant women aim for the tightest control — often below 6%.
Don't compare your target with anyone else's without asking your doctor.
How fast should HbA1c come down?
Because HbA1c is a 3-month average, it changes slowly. Even with perfect discipline, expect it to drop by about 0.5–1% every three months. That's normal. It's not a sign that treatment isn't working — it's just how the number moves.
A sudden crash (from 10% to 6% in one month) would actually be dangerous. Your doctor wants steady, sustainable improvement.
What can throw off your reading
HbA1c can be falsely low or falsely high in a few situations: recent blood loss, iron-deficiency anaemia, chronic kidney disease, certain haemoglobin variants (common in some Indian populations).
If your finger-prick sugars look bad but your HbA1c looks great — or vice versa — mention it. Your doctor may switch to fructosamine or continuous glucose monitoring.