Prediabetes in the UK: Warning Signs, the NHS Health Check and What Actually Helps

Prediabetes means your blood sugar is higher than normal but not high enough for a type 2 diabetes diagnosis. In the UK it's usually defined as an HbA1c of 42 to 47 mmol/mol. It rarely causes symptoms, so it's usually found through a blood test, often at an NHS Health Check. The good news: lifestyle changes cut the risk of type 2 diabetes substantially, and the NHS offers free support in England.

This guide covers who's at risk, how to get checked, and what the evidence says works. For background on blood sugar and insulin, see what metabolic health really means for adults.

What is prediabetes?

Prediabetes means blood glucose levels that are higher than normal, as the NHS puts it. You may also see it called non-diabetic hyperglycaemia or being at "high risk" of type 2 diabetes.

NICE defines high risk as a fasting plasma glucose of 5.5 to 6.9 mmol/l or an HbA1c of 42 to 47 mmol/mol (6.0 to 6.4%). An HbA1c of 48 mmol/mol (6.5%) or above is the threshold for diagnosing type 2 diabetes.

It's common. Diabetes UK estimates 6.9 million people in the UK are at increased risk of type 2 diabetes based on their blood sugar levels.

Prediabetes is closely tied to how well your body responds to insulin, which we explain in what insulin sensitivity is. Muscle is one of the main places glucose goes after a meal, which is why strength training features in the advice below. NovusDNA is a UK supplement brand making clearly labelled, science-led supplements tested by Campden BRI, a UKAS-accredited UK laboratory. For people building a strength routine, NovusDNA Micronised Creatine supports training performance, with an authorised claim for physical performance in short bursts of high-intensity exercise. It isn't a treatment for prediabetes, and no supplement is.

What are the warning signs?

Usually there aren't any. Diabetes UK says there aren't usually any symptoms, which is why knowing your risk factors matters more than waiting for signs.

The NHS says your risk of type 2 diabetes is higher if you:

1. are white and over 40, or over 25 and from a South Asian, Chinese, Black African or Black Caribbean background

2. have a parent, brother or sister with type 2 diabetes

3. are overweight and not very physically active

4. have high blood pressure

Diabetes UK adds that a large waist measurement raises risk, that anyone who had gestational diabetes should have regular blood glucose tests afterwards, and that prediabetes can affect people of a healthy weight too.

You can check your risk in about five minutes with Diabetes UK's free Know Your Risk tool. You'll need a tape measure and scales.

How to get checked: the NHS Health Check

In England, the NHS Health Check is for people aged 40 to 74 without conditions such as heart disease, diabetes or stroke. You should be invited by your GP or local council every five years.

The check takes about 20 to 30 minutes and covers blood pressure, cholesterol, BMI and your diabetes risk, which may include a blood sugar test. Some areas offer it online. If you're outside the age range, haven't been invited, or live in Scotland, Wales or Northern Ireland, ask your GP about a blood test if you're concerned.

What actually helps

1. The NHS Diabetes Prevention Programme (Healthier You)

If a blood test shows prediabetes, NHS England offers a free nine-month lifestyle programme, in person or digitally. It cuts the risk of type 2 diabetes by more than a third for people who complete it, and NICE recommends that people at high risk are referred to this kind of programme.

Real-world data back it up. In an observational study of NHS patient records, people referred had a 20% lower rate of progressing to type 2 diabetes than those who weren't. In the first national results, completers lost an average of 3.3 kg (Diabetes Care).

2. Lifestyle change works

The landmark US Diabetes Prevention Program trial found a lifestyle programme cut the incidence of type 2 diabetes by 58%, compared with 31% for the medicine metformin. A Finnish trial found the same 58% reduction.

On weight, Diabetes UK says losing 1% to 9% of your body weight can help insulin work better, and that health changes can return blood sugar to the normal range for some people. It also notes that not everyone with prediabetes needs to lose weight.

3. Move more, and break up sitting

The NHS guidelines are 150 minutes of moderate activity a week, plus strengthening activities for all the major muscle groups on at least two days. Diabetes UK explains that activity helps insulin work better and that breaking up long periods of sitting can help lower blood sugar. A 10-minute walk after a meal is a good place to start.

We explain how muscle and movement link to blood sugar in why strength and everyday movement matter for metabolic health.

Do supplements help with prediabetes?

Not in any proven way, and a supplement brand saying otherwise should worry you. Diabetes UK doesn't recommend herbal remedies or supplements for diabetes because there isn't enough evidence they're safe and effective, and points out that "natural" doesn't necessarily mean safe. The US National Center for Complementary and Integrative Health agrees that for most supplements there's no evidence of benefit, and warns against replacing medical care with unproven products.

Berberine is often promoted for blood sugar, but its safety is under review. The European Food Safety Authority's draft opinion, endorsed in January 2026, said the available data don't allow a safe intake to be established and flagged a risk of interactions with medicines, and the UK Committee on Toxicity has been reviewing it. If you have prediabetes and are considering any supplement, speak to your GP or pharmacist first.

FAQ

What HbA1c level is prediabetes in the UK?

An HbA1c of 42 to 47 mmol/mol (6.0 to 6.4%), or a fasting plasma glucose of 5.5 to 6.9 mmol/l, according to NICE. An HbA1c of 48 mmol/mol (6.5%) or above is used to diagnose type 2 diabetes. Your GP can explain what your result means for you.

Can prediabetes be reversed?

For many people, blood sugar can return to the normal range with lifestyle changes, though not everyone will get there and ongoing checks still matter. In major trials, lifestyle programmes cut progression to type 2 diabetes by 58%, and NHS England says completing Healthier You cuts risk by more than a third. Diabetes UK notes that not everyone with prediabetes needs to lose weight.

Who should get an NHS Health Check?

In England, adults aged 40 to 74 who don't already have heart disease, diabetes, stroke or certain other conditions should be invited every five years by their GP or local council. The check takes about 20 to 30 minutes and includes a diabetes risk assessment. If you live elsewhere in the UK, ask your GP about checks.

Can supplements prevent type 2 diabetes?

There's no good evidence that they can. Diabetes UK doesn't recommend herbal remedies or supplements for diabetes because there isn't enough evidence they're safe and effective, and some, such as berberine, may interact with medicines. The most effective steps are the ones in the Healthier You programme: diet, activity and, where needed, weight loss.

How do I get referred to Healthier You?

Speak to your GP. People in England with a recent blood test showing prediabetes can usually be referred, and NHS England offers both face-to-face and digital versions of the nine-month programme.

Prediabetes in the UK is common, usually silent and often improvable. Check your risk, take up an NHS Health Check if you're offered one, and ask your GP about Healthier You if your results are raised. The changes that work are everyday ones: moving more, building strength, sitting less and, for many people, losing a little weight.

If you'd like help working out where supplements do and don't fit around those changes, the NovusDNA Start Here guide asks six quick questions and suggests a starting point.

This article is for general information and isn't medical advice. If you're worried about your blood sugar, speak to your GP. Food supplements should not replace a varied, balanced diet and healthy lifestyle, and are not intended to prevent, treat or cure any disease.