What Does Prediabetic Mean? UK Guide

Prediabetic means having blood glucose levels that are higher than normal but not yet high enough to be diagnosed as type 2 diabetes. In the UK, this state is also called non-diabetic hyperglycaemia (NDH). It is an intermediate metabolic condition in which the body's cells have become less responsive to insulin, raising the risk of progressing to type 2 diabetes if left unaddressed. The good news is that prediabetes is often reversible through lifestyle changes, and the NHS offers structured support to help people reduce their risk. This article explains the diagnostic thresholds, risk factors, symptoms and available NHS support.

What does prediabetic mean and how is it diagnosed in the UK?

Prediabetic means blood glucose is above normal but below the type 2 diabetes threshold; in the UK it is diagnosed by HbA1c or fasting plasma glucose, usually arranged by a GP.

Prediabetic means that a person's blood glucose levels are higher than normal but not yet high enough to meet the diagnostic threshold for type 2 diabetes. In UK clinical practice, this state is also referred to as non-diabetic hyperglycaemia (NDH), and the two terms are used interchangeably. The condition describes an intermediate metabolic state in which the body's cells have become less responsive to insulin, a hormone produced by the pancreas to regulate blood sugar. Without intervention, prediabetes can progress to type 2 diabetes, though this is not inevitable.

In the UK, prediabetes or NDH is most commonly identified through one of two blood tests. The HbA1c test measures average blood glucose over the preceding two to three months and is the preferred diagnostic tool in primary care for most adults. A fasting plasma glucose (FPG) test, taken after an overnight fast, may also be used. Both tests are typically arranged by a GP, often as part of a routine health check or NHS Health Check.

HbA1c is not suitable for diagnosing diabetes or NDH in pregnancy; pregnant women should follow their maternity diabetes pathway, which uses different tests.^[1] HbA1c may also give unreliable results in people with conditions that affect red blood cell turnover, such as iron-deficiency anaemia, haemoglobinopathies, chronic kidney disease or those who have had a recent blood transfusion. In these situations, a clinician may use a fasting plasma glucose test or an oral glucose tolerance test (OGTT) instead.

Diagnosis is usually made incidentally, for example during investigations for another condition, or through targeted screening of people known to be at higher risk. The NHS Diabetes Prevention Programme uses validated risk tools, including the Leicester Risk Assessment, to identify individuals who may benefit from testing. Once identified, people with prediabetes are offered structured support rather than medication in the first instance, reflecting the strong evidence that lifestyle change can alter the trajectory of the condition. NICE guidance (NG215) does note, however, that metformin may be considered for people at high risk when lifestyle measures are insufficient or not possible; this decision is made by a clinician on an individual basis.^[15][16]

What blood sugar levels put you in the prediabetic range?

An HbA1c of 42 to 47 mmol/mol or a fasting plasma glucose of 6.1 to 6.9 mmol/L places an adult in the UK prediabetic range, according to NHS and NICE guidance.

In the UK, an HbA1c reading of 42 to 47 mmol/mol places a person in the prediabetic range (non-diabetic hyperglycaemia), according to NHS and NICE guidance (NG28).^[2][14] Below 42 mmol/mol is considered normal, while 48 mmol/mol or above on two separate occasions is generally diagnostic of type 2 diabetes in adults without symptoms.^[2][14] These thresholds apply to adults; children and people who are pregnant follow different diagnostic pathways.

For fasting plasma glucose, the prediabetic range is 6.1 to 6.9 mmol/L. A fasting result of 7.0 mmol/L or above, confirmed on a second test, is consistent with a diagnosis of type 2 diabetes. It is worth noting that HbA1c and fasting glucose do not always give equivalent results in the same individual, and a clinician will interpret findings in the context of the person's overall health.

In some circumstances, an oral glucose tolerance test (OGTT) is used. This measures blood glucose two hours after a standard glucose drink. A two-hour result of 7.8 to 11.0 mmol/L indicates impaired glucose tolerance (IGT), which is another form of prediabetes. A result of 11.1 mmol/L or above is consistent with type 2 diabetes. The OGTT is more commonly used in pregnancy and in cases where HbA1c or FPG results are inconclusive or unreliable.

These figures are not arbitrary cut-offs. Research underpinning NICE guidance has shown that the risk of cardiovascular complications and progression to type 2 diabetes rises progressively across the prediabetic range, even before the diabetes threshold is crossed.^[3][7] This is why early identification matters. People whose results fall in the prediabetic range should not wait for a formal diabetes diagnosis before making changes, as the window for effective intervention is widest at this stage.

Who is most at risk of developing prediabetes?

People with a BMI above 25 kg/m², a family history of type 2 diabetes, physical inactivity, previous gestational diabetes or certain ethnic backgrounds face the highest risk of prediabetes.

Several well-established risk factors increase the likelihood of developing prediabetes, with excess body weight, physical inactivity and a family history of type 2 diabetes among the most significant. People with a body mass index (BMI) above 25 kg/m² are at elevated risk, and the threshold is lower, at 23 kg/m², for people of South Asian, Chinese, African-Caribbean or Black African heritage, reflecting differences in metabolic risk at lower body weights, as set out in NICE public health guidance.^[5][4]

Age is also a relevant factor, with risk increasing from around 40 years onwards in the general population and from 25 years in higher-risk ethnic groups.^[4][7] Other recognised risk factors include:

• A previous diagnosis of gestational diabetes

• Polycystic ovary syndrome (PCOS)

• High blood pressure or a history of cardiovascular disease

• Certain medicines, including long-term corticosteroids and some antipsychotics

• A waist circumference above 80 cm in women or 94 cm in men; lower thresholds apply for some ethnic groups (for example, 90 cm for South Asian men), in line with NHS and NICE guidance^[5][6]

Socioeconomic factors also play a role. People living in areas of higher deprivation are more likely to have risk factors such as poor diet, limited access to green space for physical activity and higher rates of obesity. The NHS Health Check, offered to adults aged 40 to 74 in England who are not already on a disease register, is designed to identify people in these higher-risk groups before complications develop.^[9]

Can prediabetes be reversed with lifestyle changes?

Yes, prediabetes can be reversed in many people through sustained weight loss, increased physical activity and dietary improvement, though ongoing monitoring is needed as levels can rise again.

Prediabetes can be reversed in many people through sustained lifestyle changes, particularly those targeting body weight, diet quality and physical activity levels. NICE guidance (NG215) and evaluations of the NHS Diabetes Prevention Programme indicate that structured lifestyle interventions can substantially reduce the risk of progression to type 2 diabetes in people with non-diabetic hyperglycaemia, though individual outcomes vary.

The most effective changes include:

• Achieving and maintaining a modest reduction in body weight; even 5 to 10 per cent of starting weight can meaningfully improve insulin sensitivity^[4][7]

• Increasing physical activity to at least 150 minutes of moderate-intensity exercise per week, in line with the UK Chief Medical Officers' physical activity guidelines^[10][11]

• Reducing intake of refined carbohydrates, added sugars and foods high in fat and free sugars

• Increasing dietary fibre through vegetables, pulses and wholegrains

For people at high risk where lifestyle measures are insufficient or not possible, NICE (NG215) recommends that a clinician considers whether metformin is appropriate. This is a clinician-led decision and not a substitute for lifestyle change.

It is important to understand that reversal does not mean permanent immunity. HbA1c levels can rise again if weight is regained or activity levels fall, so ongoing monitoring remains important even after levels return to the normal range. A GP or practice nurse can advise on how frequently blood tests should be repeated.

For people who are considering structured support for weight management alongside lifestyle advice, a range of options exists. Bolt Pharmacy is a GPhC-registered UK online pharmacy offering online weight-management consultations, with prescriber review and pharmacist support, where clinically appropriate options may be discussed. Referral to a community dietitian or the NHS Diabetes Prevention Programme is also available through a GP.

What symptoms should you watch for and when to see your GP?

Prediabetes rarely causes symptoms, but persistent fatigue, increased thirst, frequent urination or slow wound healing warrant a GP appointment, especially if risk factors are present.

Prediabetes itself rarely causes noticeable symptoms, which is one reason it often goes undetected without screening. However, some people may notice subtle signs that warrant a GP appointment, including persistent fatigue, increased thirst, more frequent urination than usual or slow healing of minor cuts and grazes. These symptoms overlap with those of early type 2 diabetes and should not be ignored.

Dark, velvety patches of skin in body folds such as the neck, armpits or groin, a condition called acanthosis nigricans, can sometimes indicate insulin resistance and are worth mentioning to a GP. Similarly, recurrent thrush or skin infections may occasionally be an early indicator of elevated blood glucose.

You should contact your GP if:

• You have one or more risk factors for prediabetes and have not had a recent blood glucose test

• You experience unexplained weight loss, extreme thirst or blurred vision, as these may suggest blood glucose has risen into the diabetic range

• A previous HbA1c result was in the prediabetic range and you have not had a follow-up test within the recommended interval

For urgent concerns, such as symptoms of very high blood sugar including vomiting, confusion or rapid breathing, contact NHS 111 for advice or, if you are severely unwell (for example, marked drowsiness, persistent vomiting with signs of dehydration, or rapid deep breathing), call 999 or go to your nearest A&E department. These symptoms require prompt assessment and should not wait for a routine GP appointment.

Suspected adverse effects from any medicine affecting blood glucose can be reported to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk.

How does the NHS support people with prediabetes?

The NHS Diabetes Prevention Programme (Healthier You) provides structured lifestyle support to people with NDH, alongside annual HbA1c monitoring and cardiovascular risk checks in primary care.

The NHS offers structured support to people identified with prediabetes or non-diabetic hyperglycaemia (NDH), primarily through the NHS Diabetes Prevention Programme (NHS DPP), known as Healthier You in England. Equivalent prevention programmes exist in Scotland (through NHS Inform and local health boards), Wales (through NHS Wales) and Northern Ireland (through the Health and Social Care system); people in those nations should ask their GP or practice nurse about locally available services.

Referral to the NHS DPP is typically made following a blood test result in the prediabetic range. Participants receive support over a period of several months, with sessions delivered in community settings or online. Evaluations by NHS England and UKHSA indicate that the programme is effective at reducing HbA1c and body weight in people who complete it, though engagement and completion rates vary.

Beyond the prevention programme, people with prediabetes are usually offered:

• Regular HbA1c monitoring, typically annually in line with NICE guidance (NG215), to track whether levels are improving, stable or rising^[8][4]

• Blood pressure and cholesterol checks, given the overlap between metabolic risk factors

• Advice on smoking cessation if relevant, as smoking worsens insulin resistance

• Signposting to community weight management services where available

Local commissioning of services is determined by Integrated Care Boards (ICBs) in England, so the specific support available may differ between areas. People who feel they are not receiving adequate follow-up after a prediabetes diagnosis are encouraged to raise this with their GP practice. Proactive engagement with available NHS services at this stage offers the best opportunity to prevent or delay the onset of type 2 diabetes.

Scientific References

1. Diabetes in pregnancy: management from preconception to the postnatal period (NG3).
2. Type 2 diabetes in adults: management (NG28).
3. Type 2 diabetes and pre-diabetes: Issues of diagnosis and definition (evidence review for PH35).
4. Type 2 diabetes: prevention in people at high risk (PH38).
5. Overweight and obesity management (NG246): Identifying and assessing overweight, obesity and central adiposity.
6. Overweight and obesity.
7. Health matters: preventing type 2 diabetes.
8. Quality standard QS167: Referring people at high risk of type 2 diabetes.
9. NHS Health Check.
10. UK Chief Medical Officers' physical activity guidelines.
11. Physical activity guidelines for adults aged 19 to 64.
12. Early Outcomes From the English National Health Service Diabetes Prevention Programme.
13. 'Finishing the race' – a cohort study of weight and blood glucose change among the first 36,000 patients in a large-scale diabetes prevention programme.
14. Blood glucose management | Type 2 diabetes in adults: management (NG28).
15. Initial medicines | Type 2 diabetes in adults: management (NG28).
16. Type 2 diabetes: prevention in people at high risk – Recommendations (PH38).

Frequently Asked Questions