Health · Diabetes · Preventive Care
Around 6.3 million people in the UK are currently living with prediabetes, according to Diabetes UK — most of them without knowing it, and most without a single symptom to warn them.
If you've just had a blood test come back with a number in an unfamiliar range, or you're wondering whether you should get checked, here's the genuinely good news first: prediabetes is the one stage in this whole picture where real, meaningful change is still very much on the table. This guide covers what prediabetes actually is, how it's diagnosed, whether there are warning signs to look for, and what actually helps reverse it.
What prediabetes actually means
Prediabetes — sometimes called “borderline diabetes,” and officially known as non-diabetic hyperglycaemia — means your blood sugar is higher than normal, but not yet high enough to be classed as type 2 diabetes. It sits in the middle: a genuine early warning, not a diagnosis of diabetes itself.
It matters because it's a signal, not a sentence. Left unaddressed, prediabetes often progresses to type 2 diabetes over time. But that progression isn't automatic or inevitable, and this is precisely the stage where lifestyle changes have the strongest, best-evidenced chance of turning things around before anything becomes permanent.
Alongside the 6.3 million with prediabetes, Diabetes UK estimates a further 4.6 million people in the UK have a diagnosis of diabetes, and 1.3 million more are living with undiagnosed type 2 diabetes. Put together, that's more than 12 million adults — roughly one in five — somewhere on this spectrum. If you've just been told you're one of them, you're in a far more common position than it might feel like right now.
The test — HbA1c and what the numbers mean
The main test used to diagnose prediabetes in the UK is HbA1c, a blood test that measures your average blood sugar over the past two to three months, rather than a single moment in time. Unlike some other blood tests, it doesn't require fasting beforehand.
The thresholds used across NHS and NICE guidance are:
An alternative test, fasting plasma glucose, can also be used, with prediabetes generally identified in a range of roughly 5.5 to 6.9 mmol/L after a period of fasting. Your GP will let you know which test they've used and what your specific number means for you.
Are there warning signs?
Mostly, no — and this is worth knowing clearly, because it explains why testing matters more than watching for symptoms.
Prediabetes typically doesn't cause any noticeable symptoms on its own. If you start to notice the classic signs associated with diabetes — excessive thirst, needing the toilet more often, unusual tiredness — that generally means things have already moved further along than the prediabetes stage. In other words, the absence of symptoms during prediabetes isn't a sign everything's fine; it's simply how this particular stage tends to behave.
This is why prediabetes is so often picked up incidentally — through an NHS Health Check, a routine blood test for something else entirely, or because a GP flagged risk factors like weight, family history, or age and suggested a check. If you've never been tested and you're over 40, or you have a family history of type 2 diabetes, it's worth asking your GP whether a check makes sense for you.
Can you reverse prediabetes?
Genuinely, often yes — and this is the part that sets prediabetes apart from an established diabetes diagnosis.
What the evidence shows
Research into structured lifestyle programmes shows that a meaningful proportion of people with prediabetes — often cited around 30 to 40% — bring their blood sugar back into the normal range through sustained changes to diet, activity and weight. More broadly, up to half of all cases of type 2 diabetes may be preventable or delayable through the same kind of intervention, according to NHS-aligned guidance.
None of this means it happens automatically, or that it's simple. It takes real, sustained change, and it doesn't work the same way for everyone — some people find their numbers improve quickly, others need longer, and a smaller number find lifestyle change alone isn't quite enough and need medical support alongside it. But the central point is genuinely encouraging: at this stage, the trajectory isn't fixed. What you do next has a real chance of changing where this goes.
What actually helps — diet and lifestyle
The advice given through NHS pathways for prediabetes tends to focus less on any single “magic” food and more on overall dietary patterns.
Worth reducing
- Highly processed and red meat
- Refined carbohydrates — white bread, white rice, sugary cereals
- Sugar-sweetened drinks
- Foods high in saturated fat, low in fibre
Tends to be recommended
- Mediterranean-style eating
- Plant-based or largely vegetarian diets
- Moderate-carbohydrate approaches with whole grains, vegetables, legumes
The specific approach that works best is genuinely individual, and worth discussing with a GP or dietitian rather than adopting a strict plan from the internet.
Alongside diet, weight management (even a modest reduction, if you're carrying excess weight, tends to have a real effect) and regular physical activity are the two other pillars that come up consistently in the evidence. None of this needs to happen overnight, and small, sustained changes tend to outperform dramatic short-term ones.
The NHS Diabetes Prevention Programme
If you're diagnosed with prediabetes in England, your GP can refer you to the NHS Diabetes Prevention Programme, sometimes called Healthier You.
What it actually offers
It's free, and it's specifically built around structured behaviour change — not a leaflet handed over at the end of an appointment, but ongoing support with diet, activity and, where useful, weight management.
It's worth asking your GP directly whether you're eligible and how to get referred, rather than waiting for it to be offered — referral doesn't always happen automatically, and it's a genuinely useful resource that many people don't know exists until they ask.
Once you've been identified as having prediabetes, the usual follow-up is an annual HbA1c check, sooner if any symptoms develop in the meantime — a good moment to also ask your GP what your own personal risk factors and next steps look like.
How Hea fits in
If you've just been told you have prediabetes, one of the hardest parts is simply remembering to actually follow through — not because you don't care, but because life doesn't pause to make space for a new habit, and the yearly check can feel a long way off in the meantime.
Hea can send a gentle reminder when your annual HbA1c check is coming up, and give you somewhere to note how diet or activity changes are actually going, day to day — not to replace the test itself, but to help make sure the follow-up doesn't quietly slip past unnoticed.
Hea
Your free 24/7 health companion for life with a diagnosis
Because managing a condition shouldn't feel like managing a job. Hea works for people living with type 1 and type 2 diabetes, prediabetes, and many other long-term conditions — remembering your history, connecting the dots between symptoms, and turning weeks of conversation into a one-page summary your GP can read in minutes.
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Frequently asked questions
What are the symptoms of prediabetes?
Usually, there aren't any. Prediabetes tends to be symptom-free, which is exactly why it's typically discovered through routine testing rather than noticed independently. If classic diabetes symptoms — excessive thirst, frequent urination, unusual tiredness — do appear, that generally suggests things have progressed beyond the prediabetes stage.
Can prediabetes be reversed without medication?
Often, yes. Structured lifestyle change — diet, activity, and weight management where relevant — brings blood sugar back into the normal range for a meaningful proportion of people with prediabetes, without medication being necessary. Some people do need additional support, which is worth discussing individually with a GP.
What is a good diet for prediabetes in the UK?
NHS-aligned guidance generally favours reducing refined carbohydrates, sugar-sweetened drinks, and processed or red meat, in favour of patterns like Mediterranean-style eating, plant-based diets, and whole grains with plenty of vegetables. The specific right approach varies by person, so it's worth a conversation with a GP or dietitian rather than a one-size-fits-all plan.
How is prediabetes diagnosed?
Usually with an HbA1c blood test, which measures average blood sugar over the past two to three months and doesn't require fasting. A result of 42–47 mmol/mol falls in the prediabetes range, compared with below 42 for normal and 48 or above for type 2 diabetes.
Sources
- Diabetes UK, Prediabetes and non-diabetic hyperglycaemia — diabetes.org.uk
- NICE, Type 2 diabetes: prevention in people at high risk (PH38)
- NHS, NHS Diabetes Prevention Programme (Healthier You) — england.nhs.uk
- NHS Scotland, Right Decisions, Testing for prediabetes
