HbA1c measures the proportion of haemoglobin coated with glucose, reflecting your average blood sugar over roughly twelve weeks. It is the anchor of diabetes care — but it is an average, and averages hide swings.
What target applies to you
Below 7% suits most adults. Older patients, those living alone, or anyone with frequent hypoglycaemia are often better served by a target of 7.5–8%. A target is a clinical decision, not a universal rule.
How often to repeat it
Every three months while treatment is being adjusted, every six months once stable. Testing earlier than eight weeks after a change rarely gives useful information.
When the number misleads
Anaemia, recent blood loss, pregnancy and kidney disease all distort HbA1c. In those situations fasting glucose and post-meal readings carry more weight.
- Iron deficiency can raise it falsely
- Haemolysis can lower it falsely
- Pregnancy needs separate targets
Pair it with daily readings
A comfortable HbA1c with frequent highs and lows is not good control. Home glucose logs, or a short period of continuous monitoring, reveal the pattern behind the average.
Key takeaways
- Under 7% is typical, but targets are individual
- Repeat every three to six months, not sooner
- Anaemia and kidney disease distort the result
