What average blood sugar does my HbA1c mean?
About 7.8 mmol/L if your HbA1c is 48 (6.5%). Every 11 mmol/mol more adds about 1.6 mmol/L. But it’s a guess: most people on 53 in the study averaged anywhere from 6.8 to 10.3.
On this page
What average glucose does my HbA1c match?
An HbA1c of 48 (6.5%) matches an average of about 7.8 mmol/L. At 53 (7%) it’s about 8.6. The figures come from the ADAG study, which took about 2,700 glucose readings from each person over 3 months.
HbA1c is sugar stuck to your red blood cells. Those cells last around 2 to 3 months, so the test shows your average over that time.
UK labs give it in mmol/mol. The % is the older unit, used before 2009.
| HbA1c mmol/mol (%) | Average glucose (mmol/L) | Most people in the study |
|---|---|---|
| 31 (5%) | 5.4 | 4.2 to 6.7 |
| 42 (6%) | 7.0 | 5.5 to 8.5 |
| 48 (6.5%) | 7.8 | Not published |
| 53 (7%) | 8.6 | 6.8 to 10.3 |
| 58 (7.5%) | 9.4 | Not published |
| 64 (8%) | 10.2 | 8.1 to 12.1 |
| 75 (9%) | 11.8 | 9.4 to 13.9 |
| 86 (10%) | 13.4 | 10.7 to 15.7 |
Sources: ADAG study; NGSP; NICE NG28
Between two rows? Every 11 mmol/mol, or 1%, adds about 1.6 mmol/L.
Next, check where your HbA1c sits on the scale further down. For what each band means, see normal HbA1c levels.
How do I convert HbA1c to mmol/L?
Go to % first, then to mmol/L. The NGSP sets the first step. The ADAG study gives the second.
| To get | Do this | Example |
|---|---|---|
| mmol/mol to % | Times 0.09148, then add 2.152 | 42 gives 6.0% |
| % to mmol/mol | Times 10.93, then take away 23.5 | 6.5% gives 48 |
| % to average glucose | Times 1.5944, then take away 2.594 | 6% gives 7.0 mmol/L |
| Average glucose to % | Add 2.594, then divide by 1.5944 | 10 mmol/L gives 7.9% |
Sources: NGSP; ADAG study
Got an average from your meter or sensor instead? Run the last row. An average of 10 works out at about 7.9%, or 63 mmol/mol.
Write down the result. You’ll need it to read the scale below.
Why is the average only a guess?
It’s worked out from your HbA1c, not measured. Think of guessing height from shoe size. It works on average, but people with the same size can be quite different heights.
That’s the 6.8 to 10.3 spread. In the study, most people on 53 (7%) had a true average somewhere in that range. So your number is a fair guess, not a reading of your blood.
It fits some people less well. The study left out people with anaemia, long-term kidney or liver disease, blood loss or a transfusion. It also left out children and pregnant women.
Anything that changes how long your red blood cells last can upset HbA1c. Low iron (iron deficiency anaemia), for example, can push it up.
What to do with your converted number
- Write down your HbA1c in mmol/mol, the % and the test date.
- Read your average from the table and treat it as a rough guide.
- Expect single finger-prick readings to sit above and below that average.
- Tell your GP if you have anaemia or kidney disease, or are pregnant, as HbA1c may not tell the full story.
- Ask your GP or diabetes team which HbA1c to aim for.
- Never stop or change a prescribed medicine without your prescriber.
Sources: Diabetes UK; NHS lab (Gloucestershire)
Wear a sensor? See CGM vs HbA1c for why the two can differ.
Is my HbA1c normal, at risk or diabetes?
Diabetes UK says 48 or above is diabetes. From 42 to 47, you’re at risk of type 2, often called prediabetes. In average glucose terms, that’s from about 7.0 to just under 7.8.
There’s no UK average glucose cut-off; the bands are set in HbA1c.
- Below 42 mmol/molBelow the at-risk level.
- 42 to just under 48 mmol/molAt risk of type 2 diabetes.
- 48 mmol/mol or aboveDiabetes range. Retest if you had no symptoms.
Sources: Diabetes UK; NHS lab (Gloucestershire)
On 48 or more with no symptoms? You’ll need a second test to confirm it.
On 42 to 47? An NHS lab advises a check at least once a year. Our guide on how to lower HbA1c covers what helps.
What HbA1c should I aim for with diabetes?
Diabetes UK says 48 (6.5%) or below is ideal. That’s an average of about 7.8.
For type 2, NICE sets a higher aim if your medicine can cause low blood sugar, called a hypo. With type 1, the aim stays at 48 or lower.
| Who | HbA1c aim | Average glucose, about |
|---|---|---|
| Type 1 | 48 (6.5%) or lower | 7.8 or lower |
| Type 2, on diet or a medicine that doesn’t cause hypos | 48 (6.5%) | 7.8 |
| Type 2, on a medicine that can cause hypos | 53 (7.0%) | 8.6 |
| Type 2, risen to 58 (7.5%) or more on first medicine | 53 (7.0%), with more medicine | 8.6 |
Sources: NICE NG17; NICE NG28; ADAG study
Your aim is personal. NICE says to agree it with you, and it may be relaxed for people who are older or frailer.
Day to day, NICE’s type 1 meter aims are 5 to 7 on waking and 4 to 7 before other meals. With type 1, if you check after meals, aim for 5 to 9 at least 90 minutes after eating.
Never stop or change a prescribed medicine without your prescriber. More on day-to-day readings in blood sugar levels with diabetes.
When to speak to a GP
Not everyone with type 2 diabetes has symptoms. Book an appointment if:
- Your HbA1c is 48 or more. If you had no symptoms, you’ll need a second test to confirm it.
- Your HbA1c is 42 to 47. Ask about a check at least once a year.
- You feel very tired, pee more than usual, feel thirsty all the time or lose weight without trying. Blurred vision, cuts that heal slowly, itching around your penis or vagina, or thrush that keeps coming back can also be signs.
- You have anaemia or kidney disease and your HbA1c doesn’t match your meter. These can upset HbA1c.
Think you or your child has type 1 diabetes? Ask for an urgent GP appointment or call 111.
Have you or your child been peeing more and feeling very thirsty and tired, and it’s getting worse quickly? Call 999 or go to A&E. Same if you also have stomach pain or diarrhoea, feel or are sick, feel sleepy or confused, or breathe faster and deeper than usual.