Metabolic health
Blood Sugar Levels by Age: Does Normal HbA1c Change as You Age?
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed August 20267 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
QUICK ANSWER
UK labs use one HbA1c threshold at every age. Under 42 mmol/mol is normal, 42 to 47 means raised risk, and 48 or above needs review. But HbA1c does creep up with age. In healthy adults the upper limit runs near 42 in your twenties and near 47 past 60, so a 44 at 70 is common.
Not sure which markers you need? Build your test →You are 66. Your HbA1c comes back at 44, and the letter uses the word prediabetes. Nothing about your diet changed this year. So the question lands hard: is 44 a warning, or is it simply what 66 looks like?
This guide answers that honestly. It covers the UK thresholds, how much HbA1c really shifts with age, and why the age charts you find elsewhere are averages wearing a target's clothing.
1. What counts as a normal blood sugar level in the UK?
Under 42 mmol/mol is the number to know. Most UK blood sugar questions are really HbA1c questions. HbA1c measures how much sugar has attached to your red blood cells. Because those cells live a few months, it gives an average rather than a snapshot. Our guide to normal HbA1c levels reads each band in turn.
Diabetes UK puts it simply: the test “tests your average blood sugar levels for the last two to three months”. The UK bands are flat, and they read the same whether you are 25 or 85.
HbA1c chart: mmol/mol and the old % units
UK labs have reported in mmol/mol since 2011. Plenty of charts, apps and American articles still use the old percentage, which is why one result can look like two different numbers.
| HbA1c | Old % units | What it is called |
|---|---|---|
| 36 mmol/mol | 5.4% | Normal |
| 40 mmol/mol | 5.8% | Normal, near the top of it |
| 42 mmol/mol | 6.0% | Raised risk starts here |
| 44 mmol/mol | 6.2% | Raised risk, often called prediabetes |
| 46 mmol/mol | 6.4% | Raised risk, at the top of the band |
| 48 mmol/mol | 6.5% | Needs clinical review |
| 53 mmol/mol | 7.0% | Well above the review threshold |
The two scales are tied together by the IFCC-NGSP master equation: subtract 2.15 from the percentage and multiply by 10.929. Our HbA1c converter does it for any value, in either direction.
“HbA1c ≥48 mmol/mol can be used to diagnose diabetes in most situations.”
— Gloucestershire Hospitals NHS Foundation Trust, Pathology
Hold on to those three words: in most situations. The rest of this guide is about the situations where the flat threshold tells you less than it seems to.
2. Does HbA1c rise with age?
Yes, and the rise is real rather than a measurement quirk. A 2008 study in Diabetes Care tracked 2,473 people in the Framingham Offspring Study and 3,272 in the US NHANES survey. HbA1c rose by 0.014 and 0.010 percentage points a year in the two groups.
That works out at roughly 1 mmol/mol per decade. The important part is what the authors ruled out. The link held after they excluded people with impaired glucose tolerance, and after adjusting for sex, body weight and glucose levels. Age moved the number on its own.
German researchers then asked what a healthy range would look like per age band. Writing in BMC Endocrine Disorders, they used 1,804 healthy adults from two population studies. Their upper limits climbed steadily.
| Age | Upper limit | Old % units |
|---|---|---|
| 20 to 39 | 42.1 mmol/mol | 6.0% |
| 40 to 59 | 43.2 mmol/mol | 6.1% |
| 60 and over | 47.5 mmol/mol | 6.5% |
What is a normal HbA1c at 70?
On an NHS result, the same three bands apply at 70 as at 30. Under 42 is normal. 42 to 47 is raised risk. 48 or above needs review.
The German study grouped everyone over 60 together, so it has no separate figure for 70. In that group, the upper limit was 45.4 mmol/mol for men and 47.5 for women. So a reading in the low to mid 40s is common at 70. It still deserves a repeat test and a conversation, because age does not cancel the risk.
3. Is there an official blood sugar chart by age in the UK?
No, and that matters more than any chart. UK labs use one set of bands at every adult age. The NHS publishes no age-banded normal range for HbA1c.
So the age charts elsewhere online are averages dressed up as targets. An average says what is common at your age, not what is healthy for you. Plenty of 70-year-olds sit under 40.
The German authors were blunt about the consequence. Higher HbA1c values in older people, they wrote, “would currently lead to the diagnosis of diabetes according to the guidelines which do not take the increase of HbA1c with age into account”. That is a case for reading a borderline number in context, not for ignoring it.
Context also beats guesswork. If tingling feet are what brought you here, read this number before you buy benfotiamine, which failed its largest trial in 2026. The same rule applies to the spice aisle, as cinnamon and blood sugar sets out.
4. When does a raised HbA1c actually matter?
The direction matters more than the dot. A single reading in the 42 to 47 band is a prompt to look again, not a verdict. Where there are no symptoms, UK practice is to confirm a raised result with a second test before anything follows from it.
The band is also where the most good can be done. The NHS Diabetes Prevention Programme exists for exactly this group. NICE guidance (PH38) recommends yearly retesting for people at high risk.
These patterns deserve a GP conversation whatever your age:
- An HbA1c that climbs across repeated tests.
- A result of 48 or above, on any single test.
- Thirst, frequent urination, blurred vision or unexplained weight loss.
- A big jump from your own previous reading.
- A family history of type 2 diabetes, or a South Asian or Black African background.
5. What else moves your HbA1c?
HbA1c is measured on your red blood cells, so anything that changes how long those cells live will move the result. None of this involves your diet.
- Iron deficiency makes red cells live longer, which can nudge HbA1c up.
- Recent blood loss or a transfusion works the other way and can push it down.
- Pregnancy and advanced kidney disease both make HbA1c unreliable on its own.
- Steroid medication can raise blood sugar quickly, faster than HbA1c reflects.
This is why a full blood count is useful next to a borderline HbA1c. It shows whether your red cells are behaving normally. Our anaemia guide covers the iron side in more depth.
6. Why one result does not settle it
Most charts leave this part out, and it matters if your number landed near a line. Diabetes UK publishes the criteria clinicians work to.
“In a person without symptoms of diabetes, a diagnosis of diabetes should not be made on a single HbA1c result.”
— Diabetes UK, diagnostic criteria for diabetes
The process is a repeat test. A first result of 48 mmol/mol or above is repeated, and the diagnosis follows only if the second agrees. The exception is symptoms. With the classic signs, thirst, weight loss and passing a lot of urine, one result is enough.
The same source names where HbA1c must not be used to diagnose at all.
- All children and young people.
- Anyone of any age where type 1 diabetes is suspected.
- People who have had symptoms for less than two months.
- Pregnancy, where different tests are used.
So a 44 at 70 reads calmer than it feels. It is a prompt to look again in a few months. Our guide to lowering HbA1c covers what actually moves the number in that time.
7. Which blood test shows your HbA1c
The marker you want is HbA1c. One reading tells you where you sit today. Two readings, months apart, tell you the thing that actually matters: the direction of travel.
Helvy's Advanced Heart Health panel (£159) reports HbA1c alongside ApoB, Lp(a), hs-CRP and a full cholesterol breakdown. Those markers belong together, because blood sugar and heart risk track each other closely. It is a home finger-prick test, processed by UKAS-accredited UK labs.
One honest limit: we do not offer fasting glucose or fasting insulin in our home panels, because both need a venous sample rather than a finger-prick. HbA1c works well from a finger-prick, and it needs no fasting.
To assemble your own marker list, the build-my-test tool walks you through it.
READY TO TEST?
Know your blood sugar trend, not just today's number
Helvy's home blood tests report HbA1c with plain-English context, so a borderline result never sparks a needless panic. Samples are processed by UKAS-accredited UK labs.
For a result above the line rather than the bands themselves, see what a high HbA1c means and the two-week repeat NHS labs ask for.
Frequently asked questions
Can one HbA1c result diagnose diabetes?
Not by itself in someone without symptoms. Diabetes UK states that a diagnosis should not be made on a single HbA1c result. A first result of 48 mmol/mol or above is repeated, and the diagnosis follows only if the second agrees.
When should HbA1c not be used to diagnose diabetes?
Diabetes UK excludes all children and young people, anyone suspected of type 1 diabetes, people with symptoms for under two months, and pregnancy. Conditions affecting red blood cells, including iron deficiency and recent blood loss, can also skew the reading.
What is a normal HbA1c by age, according to the NHS?
UK labs use one set of HbA1c bands at every adult age. Under 42 mmol/mol is normal, 42 to 47 means raised risk, and 48 or above needs review. Research in healthy adults puts the upper limit near 42 mmol/mol under 40, and near 47.5 past 60. Those are research figures, not UK reference ranges.
What is a normal HbA1c for a 70 year old?
NHS labs use the same bands at 70: under 42 mmol/mol is normal, 42 to 47 is raised risk, and 48 or above needs review. In a German study of healthy adults over 60, the upper limit was 45.4 for men and 47.5 for women. A low 40s reading is common at 70, but still worth a repeat.
Is an HbA1c of 44 normal at 65?
It is common at that age. A 44 falls in the 42 to 47 band that UK practice calls raised risk, and that label applies at every age. Research on healthy older adults suggests 44 sits inside the normal spread past 60. The same 44 at 30 would prompt a closer look. Ask a qualified clinician to read yours in context.
How much does HbA1c rise with age?
A 2008 Diabetes Care study of the Framingham Offspring Study and NHANES found rises of 0.014 and 0.010 percentage points a year in people without diabetes. That is roughly 1 mmol/mol per decade. The link held after excluding people with impaired glucose tolerance.
Do UK labs adjust HbA1c for your age?
No. Unlike eGFR, where age sits inside the calculation, HbA1c is measured directly and compared against one flat threshold. Your age changes nothing about how the result is reported.
Should I worry about one raised HbA1c reading?
One reading rarely settles anything on its own. Where there are no symptoms, UK practice is to confirm a raised result with a second test. Iron deficiency, recent blood loss, pregnancy and kidney disease can all shift a single result. Repeat it before you draw a conclusion.
Can you lower your HbA1c?
Often, yes. HbA1c reflects the last two to three months, so it responds to sustained change rather than a good week. Weight, activity and diet are the evidence-backed levers, and the NHS Diabetes Prevention Programme is built around them. Our guide on lowering HbA1c covers the detail.
How do you convert HbA1c from % to mmol/mol?
Subtract 2.15 from the percentage and multiply by 10.929. So 6.0% is 42 mmol/mol and 6.5% is 48. To go back, divide by 10.929 and add 2.15. UK labs have reported in mmol/mol since 2011, and the percentage survives in older charts and American articles.
Related guides
HbA1c Blood Test UK
What the marker is, how it is measured, and what your number means.
Pre-diabetes Blood Test UK
The 42 to 47 band explained, and what usually happens next.
How to Lower Your HbA1c
The evidence-backed levers, and how long each takes to show up.
Glucose Blood Test UK
How a fasting snapshot differs from a three-month average.
Blood Test Reference Ranges UK
Why 'normal' on a lab report is a population range, not a target.
Advanced Heart Health Test
HbA1c, ApoB, Lp(a), hs-CRP and full cholesterol in one home test.