Non-diabetic hyperglycaemia (pre-diabetes)

What is non-diabetic hyperglycaemia (NDH)?

If you have NDH, your blood sugar (glucose) is raised beyond the normal range but it is not so high that you have diabetes; however you are at an increased risk of developing type 2 diabetes.

Up to 6 in every 10 people with NDH will develop diabetes within ten years.

The most commonly used test to identify NDH is now the HbA1c blood test. The WHO and the National Institute for Health and Care Excellence (NICE) have recommended that an HbA1c blood test level of 42-47 mmol/mol (6.0-6.4%) indicates a high risk of diabetes.

What causes non-diabetic hyperglycaemia (NDH)?

NDH develops for the same reasons as type 2 diabetes. They include:

• Being overweight or obese (most people with pre-diabetes are overweight or obese).

• Having a family history of diabetes. This refers to a close family member with diabetes - a mother, father, brother or sister.

• Doing little physical activity.

• Having other risk factors for cardiovascular disease such as high blood pressure or high cholesterol levels.

• If a woman has polycystic ovary syndrome and is also overweight.

• If you developed diabetes during pregnancy (called gestational diabetes).

NDH symptoms

• People with NDH usually have no symptoms.

• You are often found to have NDH after blood tests taken for another reason show that you have a raised blood sugar (glucose) level.

Sometimes, your doctor may suggest that a screening blood test should be taken to check your blood glucose because they are worried that you may have some risk factors for NDH or diabetes.

How common is NDH?

Many people have NDH and because there are no symptoms, they do not know that they have it. Diabetes UK estimates that around seven million people in the UK have NDH.

How is NDH diagnosed?

NDH is now most often diagnosed using a blood test called HbA1c. See the separate leaflet called Blood glucose test (blood sugar) and HbA1 for more details.

An HbA1c value of 48 mmol/mol (6.5%) or above is required to diagnose diabetes. People with an HbA1c level of 42-47 mmol/mol (6.0-6.4%) are considered to have NDH because they are at increased risk of diabetes and cardiovascular disease.

Another test to diagnose NDH is the glucose tolerance test but this is used much less often now - the most common reason for doing a glucose tolerance test is because a woman is pregnant, as HbA1c cannot be used in pregnancy. Read more in the separate leaflet called Glucose tolerance test.

NDH treatment

Treatments include:

• Referral to the Diabetes Prevention Programme.

• Lifestyle changes such as diet and exercise.

There is increasing evidence that if NDH is treated, it becomes much easier to prevent or delay it progressing to type 2 diabetes. Also, it may be possible to prevent cardiovascular disease from developing.

It is also very important to have a regular blood test (once a year) to recheck your blood sugar (glucose) level in case you develop diabetes.

Lifestyle changes

There are a number of lifestyle changes that you should adopt if you have NDH:

• Eat a healthy balanced diet. Your practice nurse and/or a dietician will give details on how to eat a healthy diet. You should aim to eat a diet low in sugar high in fibre, with plenty of fruit and vegetables:

  • Starchy foods contain carbohydrates. Standard advice is that you should continue to eat some starchy foods, although you should focus on wholegrain and wholewheat versions - so-called 'complex carbohydrates'. These tend to have a lower glycaemic index (GI) which means they are more slowly absorbed and do not raise your blood sugar as rapidly.

  • However, what many people don't realise is that starchy carbohydrates like bread, potatoes or breakfast cereals digest down into a surprisingly large amount of sugar. More and more people are discovering that by reducing the carbs (both sugary and starchy) in their diet, it is possible to lose weight and reduce blood sugar (glucose). If you do include carbs in your diet, choose complex carbs.

  • See the separate leaflet called Type 2 diabetes diet for more details.

• Lose weight if you are overweight. Getting to a perfect weight is unrealistic for many people. However, if you are overweight or obese then losing some weight will help to reduce your blood glucose level (and have other health benefits too). Losing as little as 5 - 10% of your bodyweight can have significant benefits and is often a more realistic target to start with than getting to an 'ideal' weight. See the separate leaflet called Weight reduction.

• Do some physical activity regularly. A minimum of 30 minutes of physical activity at least five times a week is advised. For example, walking, swimming, cycling, jogging, dancing - anything that makes you at least mildly out of breath and mildly sweaty. You can start slowly and build up. You can also spread the activity over the day - for example, two 15-minute spells per day. Regular physical activity also reduces your risk of having a heart attack or stroke. Always check with your doctor that it is safe to start exercising if you have been inactive for a long period. See the separate leaflet called Exercise and physical activity. The most effective treatment is lifestyle changes, including eating a healthy balanced diet, losing weight if you are overweight, and doing regular physical activity.

There are also other lifestyle changes that you can make to reduce your cardiovascular disease risk. These include:

• Stopping smoking if you are a smoker.

• Ensuring that you stick to the recommended alcohol intake. See the separate leaflet called Alcohol and sensible drinking for more details.

• Make sure that your blood pressure stays within the normal range. Have your blood pressure checked regularly with your practice nurse.

Also, discuss with your doctor or practice nurse if you need a cholesterol check and/or treatment to lower your cholesterol level.

Treatments with medicines

A number of medical trials have looked at the use of various treatments with medicines for people with NDH to see if they can help to prevent diabetes and cardiovascular disease.

Medicines that have been trialled include:

• Metformin.

• Acarbose.

• Angiotensin-converting enzyme (ACE) inhibitors.

• Angiotensin-II receptor antagonists (also known as angiotensin receptor blockers).

Lifestyle changes (as indicated above) are the most important thing if you are found to have NDH. However, the National Institute for Health and Care Excellence (NICE) has recommended that metformin should be used if a lifestyle-change programme isn't successful or isn't possible. A medicine called orlistat may occasionally also be recommended to help lose weight and therefore reduce the risk of developing diabetes. Newer medicines called GLP-1 agonists can also be used for weight loss - at the moment these are only available on the NHS from weight loss clinics, not from your GP. Availability of GLP-1 agonists varies significantly by area of the UK and there is often a long waiting list.

What follow-up is needed if you have NDH?

You will usually need a blood test to check your fasting blood sugar (glucose) level at least once a year.

This is to make sure that you have not developed diabetes. Your doctor is also likely to keep a check on any other risk factors that you may have for cardiovascular disease.

So, they may monitor your weight and your blood pressure and also suggest a blood test to check your cholesterol and triglyceride levels.

In the meantime, if you develop any symptoms of diabetes, you should visit your doctor sooner.

What are the complications of NDH?

The main complication of NDH is progression to type 2 diabetes.

NDH also increases your risk of developing:

• Heart disease.

• Peripheral arterial disease.

• Stroke (cardiovascular diseases).

• High blood pressure.

• Raised cholesterol levels.

• Weight issues.

See the separate leaflets called Cardiovascular disease (Atheroma) and Cardiovascular health risk assessment for more details.

Can NDH be prevented?

The same things that can help in preventing type 2 diabetes can help prevent NDH. These include:

• Eating a healthy balanced diet.

• Losing weight if you are overweight.

• Doing some physical activity regularly.

If you do develop type 2 diabetes, it's important to go for regular check-ups to ensure it doesn't worsen.

Referral for help and support

The NHS in England has developed the NHS Diabetes Prevention Programme for people with NDH. This provides personalised support from a group of healthcare professionals.

If you are diagnosed with pre-diabetes and live in England, you should be offered referral to this service. It involves at least 13 sessions over about 9 months, each lasting 1-2 hours. You will be supported to set and achieve goals and make positive changes to reduce your risk of developing type 2 diabetes. Most of the sessions will be run as face-to-face groups with other people who also have pre-diabetes and led by one or more experts.

Similar schemes are available in the rest of the UK.