HbA1c Normal Range UK: Charts, Targets & What Yours Means

You've had a blood test, the result has landed in your NHS app, and there it is: a number with units you've never used for anything else in your life. 44 mmol/mol. Is that fine? Is that bad? Nobody rang you, so presumably it's fine?

Not necessarily. The HbA1c normal range in the UK is narrower than most people assume, and the band just above it is where a lot of people sit for years without anyone raising it. Here is what the number measures, what yours means, and what moves it.

What HbA1c actually measures

Haemoglobin is the protein inside your red blood cells that ferries oxygen around your body. When there's glucose in your bloodstream, some of it sticks to that haemoglobin and stays stuck for the life of the cell. Glycated haemoglobin, shortened to HbA1c.

A red blood cell lives for about 120 days, as South Tees Hospitals NHS Foundation Trust puts it, and glucose attaches over that lifespan. So the proportion of your haemoglobin carrying a passenger of glucose gives a running average of how much sugar has been in your blood. Diabetes UK describes HbA1c as your average blood glucose for the last two to three months.

That's what makes the test useful. A finger-prick reading tells you about one moment. HbA1c can't be gamed by skipping breakfast or having a virtuous week before your appointment. It's the honest average.

It also means you don't need to fast for it, and it doesn't matter what time of day you go.

HbA1c normal range: the UK numbers

Here are the thresholds the NHS works to. Most UK labs report in mmol/mol; the percentages are the older DCCT units, still widely quoted and still what you'll see on American sites.

South Tees sets out the same boundary in its patient guide: a normal value for a person without diabetes is below 42 mmol/mol. That guide also lists 42 to 53 mmol/mol as ideal control for someone who already has diabetes, which is a useful reminder that "normal" and "target" answer two different questions.

If you already have diabetes, the target is different

Diabetes UK gives an ideal HbA1c of 48 mmol/mol (6.5%) or below for people living with diabetes. If you've been told you're at risk of type 2, the target drops to below 42 mmol/mol (6%).

Those aren't the same as the diagnostic thresholds, and the overlap catches people out. Someone with diabetes sitting at 47 mmol/mol is doing well. Someone without a diagnosis sitting at 47 mmol/mol has prediabetes.

Converting mmol/mol to percentages

The UK switched to mmol/mol in 2009. If you're translating an older result or an American one, the rough anchors worth memorising are 42 mmol/mol = 6.0%, 48 = 6.5%, 53 = 7.0%, and 58 = 7.5%. Every 11 mmol/mol is about 1 percentage point.

What your result actually means, band by band

Below 42 mmol/mol

Your average glucose over the past few months has been in the range seen in people without diabetes. Nothing to act on from this test alone.

One caveat. 41 and 30 are both "normal", but they are not the same. If you're at the top of the band and carrying extra weight, that's a number to keep an eye on rather than file away. Have it rechecked in a year.

42 to 47 mmol/mol: prediabetes

You don't have diabetes. You also don't have a clean bill of health, because a meaningful share of people in this band go on to develop type 2 within a few years.

The scale of it in the UK is hard to overstate. Diabetes UK reported in February 2025 that an estimated 6.3 million people are living with non-diabetic hyperglycaemia, alongside 4.6 million with a diabetes diagnosis and a further 1.3 million with undiagnosed type 2. That's more than 12 million people, or one in five UK adults, with either diabetes or prediabetes.

Prediabetes is also the most reversible stage of the whole story. Weight loss at 44 mmol/mol does a completely different job from weight loss at 60.

48 mmol/mol and above

This sits in the diabetes range. Your GP will normally repeat the test to confirm, then talk to you about treatment, and you'll be offered annual retinal screening, foot checks and regular reviews.

It is not a verdict on your character or your willpower. Type 2 diabetes is driven by genetics, age, ethnicity, medication, sleep, stress and body weight, and only one of those is something you get much say over.

Is there a normal HbA1c range by age?

This question gets searched constantly, and the honest answer is that the UK does not use age-based diagnostic thresholds. Below 42 mmol/mol is normal whether you're 25 or 75. The charts circulating online showing "normal HbA1c by age" are mostly repackaged American observational data, not clinical guidance.

What does change with age is the treatment target for people who already have diabetes. Diabetes UK notes that as people get older, a diabetes team may deliberately relax the HbA1c target, because in a frailer person the risk of a hypo and a resulting fall can outweigh the long-term benefit of tight control. That's an individual clinical decision, not a general rule about what counts as normal.

The same applies to the "normal range of HbA1c in females" question. There is no separate female threshold in UK practice. Pregnancy is the exception: HbA1c behaves differently in pregnancy and separate, tighter targets apply, so if you're pregnant or planning to be, that conversation belongs with your midwife or diabetes team rather than a chart.

Things that can skew your result

HbA1c depends on red blood cells behaving predictably, so anything that changes how long they live can shift the number without your glucose changing at all.

Diabetes UK flags that accuracy can be affected by conditions affecting red blood cells, including haemolytic anaemia, sickle cell anaemia and thalassaemia. Iron deficiency, recent heavy blood loss, a recent transfusion, chronic kidney disease and some medicines can all nudge it too.

If you have any of those and the number doesn't match how you feel, say so. There are alternative tests, and a good clinician would rather know.

How to lower a raised HbA1c

Weight is the biggest lever most people have

If you take one thing from this piece, take this. For type 2 diabetes and prediabetes driven by excess weight, losing weight does more to the number than any other single change.

The DiRECT trial, funded by Diabetes UK, put people with type 2 diabetes on a structured low-calorie programme delivered through GP surgeries. The published results showed 46% were in remission at one year and 36% at two years, meaning blood glucose back in the non-diabetes range without diabetes medication. In the five-year extension, 13% of those who kept receiving GP support were still in remission.

Most people came out of remission somewhere along the way, usually because the weight came back. Keeping it off is harder than losing it, and DiRECT doesn't pretend otherwise. But time spent in remission carries lasting benefit either way: the trial team found the weight-loss group had fewer serious health problems whether or not remission stuck.

The everyday things that help

Not glamorous, but they compound:

• Front-load protein and fibre, especially at breakfast, so the glucose curve after eating is flatter. Our guide to high protein, low calorie foods is a practical starting point.
• Walk for ten minutes after your largest meal. Muscles pull glucose out of the blood while they're working, which blunts the post-meal spike.
• Add resistance training twice a week. Muscle is where most glucose gets stored, so more of it means better disposal.
• Protect your sleep. A run of short nights raises insulin resistance measurably.
• If you smoke, stopping helps, and Diabetes UK lists it among the changes that bring HbA1c down.

If you've been doing all of this and the scale hasn't budged, we've looked at the usual culprits in why you might not be losing weight in a calorie deficit.

Where GLP-1 medication comes in

For a lot of people, diet and exercise alone don't shift enough weight to move the number meaningfully. Appetite hormones push back hard against a sustained deficit, which is biology doing exactly what it evolved to do.

This is where GLP-1 and dual-agonist medicines have changed the picture. In the SURPASS-2 trial, tirzepatide (the drug in Mounjaro) was compared against semaglutide over 40 weeks in adults with type 2 diabetes. Eli Lilly's published results showed HbA1c reductions of 2.01%, 2.24% and 2.30% at the 5 mg, 10 mg and 15 mg doses respectively, against 1.86% for semaglutide 1 mg. On the 15 mg dose, 46% of participants got their HbA1c below 5.7%.

Two caveats. That trial recruited people with diagnosed type 2 diabetes starting from an average HbA1c of 8.28%, so the size of the drop won't translate to someone sitting at 44 mmol/mol. And these are prescription medicines with side effects, mostly gastrointestinal, that need proper clinical assessment. For the fuller picture, we've written about how GLP-1 medications work and whether Mounjaro is safe.

How long does it take to change your HbA1c?

Because the test averages three months of glucose, it lags behind what you're doing now. Change your diet on Monday and retest on Friday and you'll learn nothing.

Roughly speaking, about half of the HbA1c value reflects the most recent month, with the rest spread across the two before it. So meaningful movement usually shows from around six to eight weeks, and a full picture takes about three months. That's also why the NHS retests most people every three to six months rather than more often.

If you're making changes, book the recheck for twelve weeks out and resist the urge to go earlier. Seeing a barely-moved number at week four is demoralising and tells you nothing useful.

How to get an HbA1c test in the UK

Three routes, depending on where you are.

Your GP is the first and cheapest. If you have diabetes you're entitled to at least one HbA1c a year as part of your annual review, and Diabetes UK is emphatic that this check shouldn't be skipped. If you don't have a diagnosis but you do have risk factors, such as a higher BMI, a family history of type 2, or South Asian, Black African or African Caribbean heritage, you can ask for a test rather than waiting to be offered one.

The NHS Health Check is the second route. In England it's offered to adults aged 40 to 74 roughly every five years, and it includes a diabetes risk assessment with a blood test where indicated. Scotland, Wales and Northern Ireland run their own equivalents.

Private testing is the third. Pharmacies and online labs sell HbA1c tests, usually somewhere around £20 to £40 for the single marker and more as part of a wider panel. Several are finger-prick kits you post back to a lab. They're fine for tracking a number you already know about, but an abnormal private result belongs with your GP rather than being managed alone.

Whichever route you take, ask for the actual figure rather than accepting "it's fine". Fine covers everything from 30 to 41, and those are different situations.

When to go back to your GP

A raised HbA1c on its own rarely needs urgent attention, and most people will simply be asked to make some changes and retest. Some situations do warrant a same-week appointment though.

Ring your surgery sooner if a raised result comes alongside a thirst you can't quench, passing urine much more often than usual (particularly getting up at night for it), unexplained weight loss, blurred vision, or cuts and thrush that keep coming back. Those are symptoms of glucose running high enough to matter now rather than in five years.

And if your result has jumped a long way from your last one with no obvious explanation, ask about it rather than assuming the lab made a mistake. Steroids, a new medication, a thyroid problem or an undiagnosed condition affecting your red blood cells can all be behind a sudden shift.

This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting any treatment.