Metabolic health
HbA1c: your blood sugar, averaged over three months
A finger-prick glucose is a single snapshot, high after lunch, low before breakfast. HbA1c is the running average of your blood sugar over about three months, and it's the number that actually tracks your diabetes risk.
Blood sugar is a moving target. It climbs after a meal, dips overnight, spikes with stress. So a single glucose reading tells you about one moment, which isn't much use for judging the bigger picture. HbA1c solves that by giving you an average.
Sugar that sticks
When there's glucose in your blood, a little of it sticks to the haemoglobin inside your red blood cells, and it stays stuck. Red cells live for about three months, so the amount of glued-on sugar builds a running record of how high your blood sugar has been. Measure it, and you get a three-month average in a single number. No fasting required.
What your number means
As a guide: under 42 is the healthy range, 42 to 47 signals raised risk (sometimes called pre-diabetes), and 48 or above is in the diabetes range. Diagnosis is never one number in isolation. Your doctor reads it alongside the rest of your picture.
Why HbA1c beats a one-off glucose
It responds to you
HbA1c isn't fixed. Losing a little weight, moving more, and cutting back on refined carbs can bring it down over a few months. And because it's an average, a genuine change shows up clearly rather than as daily noise.
Who should check it
- You have a family history of type 2 diabetes
- You carry extra weight, especially around the middle
- You've been told your blood sugar was 'a bit high' once and never followed up
- You want an early, honest read on your metabolic health
An HbA1c of 48 mmol/mol (6.5%) or above is used to diagnose diabetes; 42 to 47 mmol/mol indicates a high risk of developing it.
UK diagnostic thresholds (WHO / NICE)
HbA1c is included in our metabolic and longevity panels.
See the panels