Impaired fasting glycaemia
This factsheet is for people who have impaired fasting glycaemia, or who would like information about it.
Impaired fasting glycaemia (IFG) is sometimes called pre-diabetes. This is when blood glucose levels in the body are raised, but are not high enough to mean that the person has diabetes. IFG means that the body isn't able to use glucose as efficiently as it should.
About impaired fasting glycaemia
Symptoms of impaired fasting glycaemia
Complications of impaired fasting glycaemia
Causes of impaired fasting glycaemia
Diagnosis of impaired fasting glycaemia
Treatment of impaired fasting glycaemia
Impaired fasting glycaemia (IFG) means that your body isn't able to regulate glucose as efficiently as it should.
Glucose is a simple form of sugar found in foods and sugary drinks – it's absorbed as a natural part of digestion.
One function of your blood is to carry glucose around your body. When glucose reaches body tissues, such as muscle cells, it's absorbed and converted into energy. The glucose concentration in your blood is automatically regulated by a hormone called insulin.
The amount of glucose in your blood changes throughout the day. It’s higher and lower depending on what you’re eating and drinking.
Blood glucose levels can be measured in a laboratory by testing a blood sample. This is usually done when you have not eaten for eight hours and is called a fasting blood glucose test.
It’s estimated that seven million people in the UK have IFG.
IFG has no symptoms and can often go undiagnosed for years. Although there are no symptoms, many people diagnosed with IFG are overweight. Nine out of 10 people with IFG have high blood pressure, raised cholesterol levels or a family history of the condition.
IFG can increase your risk of type 2 diabetes. Many people with type 2 diabetes have no symptoms, but if you do have symptoms they might include:
- being thirsty
- passing more urine than normal
- re-occurring infections
- blurred sight
- slow healing of wounds
If you have any of these symptoms, you should talk to your GP.
IFG can lead to the development of type 2 diabetes. People with IFG are five to 15 times more likely to develop type 2 diabetes than people with normal glucose levels. However, this isn’t inevitable. You can take steps to reduce the chances of this happening. People with IFG also have a slightly increased risk of heart disease and stroke.
IFG develops if your body becomes unable to control glucose levels. Your body may be unable to use insulin properly or produce less insulin. There are a number of factors that may make you more likely to develop IFG. If you’re black or South Asian and over 25, or if you’re white and over 40, and you have one or more of the following risk factors, then you may be at risk of IFG:
- one of your parents, brother or sister has type 2 diabetes
- you’re overweight or you carry extra weight around your middle rather than your hips and thighs
- you have high blood pressure or you have had a heart attack or stroke
- you have polycystic ovary syndrome and you are overweight
- you have had diabetes during pregnancy
- you have severe mental health problems
Both IFG and diabetes are both diagnosed by testing glucose levels in the blood. The first test you will have is a fasting plasma glucose test. You will be asked not to eat anything for eight to 10 hours before a blood sample is taken.
What do the test results mean?
- If your fasting blood glucose level is between 3.6mmol/l and 6mmol/l, this means that your blood glucose level is normal.
- If your fasting blood glucose level is 7mmol/l or higher, this is likely to mean that you have diabetes. Diabetes is a long-term condition where the body is not able to control the amount of glucose in the blood.
- If your fasting blood glucose level is between 6.1mmol/l and 6.9mmols/l, you may have IFG.
Depending on the results of this test you may also be asked to have a two-hour plasma glucose test (also known as an oral glucose tolerance test, or OGTT). If you have this test, you will also be asked not to eat anything for eight to 10 hours before the blood sample is taken. After the blood sample is taken you will be asked to swallow a drink containing a known amount of glucose. Another blood test is then taken two hours after the first to see how your body has dealt with the glucose you swallowed.
IFG doesn’t need medical treatment, but it’s important to try and lower your blood glucose levels by making changes to your lifestyle. This can help to prevent, or delay the development of type 2 diabetes.
If you have had an IFG level once, you should have regular fasting glucose tests every year.
People with IFG have a greater risk of developing type 2 diabetes and are at an increased risk of heart disease and stroke, therefore it’s important to do what you can to reduce your chances of developing these conditions. You should aim to reach and maintain normal or near-normal blood glucose levels.
You can do this by:
- eating a healthy balanced diet that is low in fat, high in fibre, low in salt and including plenty of fruit and vegetables
- losing excess weight if you’re overweight and then making sure your weight stays within the recommended range for your height
- improving your fitness level by doing regular moderate physical activity (30 minutes a day at least five days a week)
As well as taking the steps above you can also reduce your risk of heart disease and stroke by giving up smoking.
Impaired fasting glycaemia Q&As
Answers to questions about impaired fasting glycaemia
Is there any other reason why my blood glucose level might be raised?
My doctor talked about metabolic syndrome - what is this?
Is impaired fasting glycaemia a type of mild diabetes?
There are some conditions and circumstances that can cause your blood glucose level to rise temporarily. This is why your GP will always check your blood glucose level a second time if you don't have any symptoms of diabetes.
As well as being an early sign of type 2 diabetes, a raised blood glucose level can also be caused by other conditions. Your GP will always check your blood glucose level at least once more if you don't have any other symptoms of type 2 diabetes, such as being thirsty or producing more urine than usual. This is because other conditions can cause a temporary rise in your blood glucose level. If these blood tests show that your blood glucose level has returned to normal, you may not need any treatment, but your GP may ask you to come back for regular checks.
There are a number of conditions and circumstances that can temporarily raise your blood glucose level. Some of these are described here.
- Some medicines can increase the level of glucose in your blood. A short period of taking steroids, for example, to treat asthma or rheumatoid arthritis, can cause a temporary increase in your blood glucose level. Other medicines including thiazide diuretics (water tablets), some antidepressants, oestrogen hormone replacement therapy (HRT) and phenytoin which is used to treat epilepsy can also cause a rise in your blood glucose level. Tell your GP if you're taking any medicines at the time of your blood test. Severe short-term stress to your body can also cause a rise in your blood glucose level. When your body is under a lot of stress it releases hormones, which have an effect on the level of glucose in your body. If you have been seriously ill following an accident or had a major operation, or if you have had a serious medical problem such as a heart attack, it's possible that your blood glucose level may increase.
- Your pancreas is a large gland in your abdomen that produces digestive juices and insulin. Insulin controls the blood glucose level in your body. Therefore, if you have a condition that affects your pancreas, such as pancreatitis, which causes your pancreas to become inflamed, your blood glucose level may be affected. You're also more likely to develop diabetes if you have pancreatitis.
- Rarer conditions to do with hormones (chemicals in your body), such as Cushing's syndrome or acromegaly, can alter your blood glucose level.
Metabolic syndrome is a collection of risk factors that can increase your risk of developing diabetes and heart disease. Metabolic syndrome doesn't always lead to diabetes. By leading a healthy lifestyle, you may be able to reduce these risk factors and prevent or delay the development of diabetes.
Metabolic syndrome is also sometimes called syndrome X or insulin resistance syndrome. If you have metabolic syndrome, it means you're likely to develop heart disease and diabetes because you have certain risk factors. A risk factor is anything that increases your likelihood of getting a disease.
There are a number of different definitions of metabolic syndrome. However, recent guidelines state that you have metabolic syndrome if you have any three of the specific risk factors outlined below.
- If you have a large waist measurement, it's known as central obesity - this increases your risk of heart disease and diabetes. This means that you store any extra weight around your middle rather than on your hips or thighs. The measurement above which your risk increases is different for men and women and also varies according to your ethnic origin. Men with a waist circumference of more than 94cm (37 inches) and women with a waist circumference of more than 80cm (32 inches) have an increased risk of heart disease and diabetes. This risk is higher if you're of South Asian origin.
- A raised level of triglycerides in your blood can increase your risk of heart disease. Triglycerides are a type of fat that mostly come from fats in your food. Energy that you eat and don't use immediately is converted into triglycerides and transported to your fat cells for storage. Although most triglycerides are stored in fat tissue, low levels are also found in your blood. A raised blood triglyceride level is 1.7mmol/l or above.
- If you have a low level of HDL cholesterol, this can increase your risk of heart disease. HDL cholesterol is the 'good' cholesterol which helps to prevent fatty deposits building up in your arteries. The values for HDL cholesterol are different for men and women. If you're a man, a level of 1mmol/l or less increases your risk of heart disease; for women the level is 1.3mmol/l or less.
- You're at an increased risk of heart disease if you have high blood pressure that is treated with medicines, or if your blood pressure is above 130/85mmHg.
- Having impaired fasting glycaemia - a fasting blood glucose level of 6mmol/l or more - is also a risk factor involved in metabolic syndrome.
- If you have metabolic syndrome, you're five times more likely to develop diabetes and three times more likely to develop heart disease than someone who doesn't have it.
You can reduce these risks by losing excess weight and increasing the amount of physical activity you do. Making these changes to your lifestyle can have a real impact on your health. Your GP may also suggest medicines to lower your blood pressure or to treat your cholesterol and triglyceride levels.
There is no such thing as mild diabetes, you either have the condition or not. Impaired fasting glycaemia means that your blood glucose level is raised but isn't yet high enough for it to mean you have diabetes. By leading a healthy lifestyle you can change these risk factors and delay the development of diabetes or even prevent it.
If you have a raised glucose level of between 6.1 and 6.9mmol/l after fasting, it doesn't mean you have mild diabetes. Impaired fasting glycaemia is what some doctors call pre-diabetes.
About one in six adults between the age of 40 and 65 in the UK has impaired fasting glycaemia. Having a raised glucose level doesn't mean you will definitely go on to develop diabetes, but it does greatly increase your risk. One study carried out in Finland showed that over a 10-year period one in 50 people with a normal blood glucose level went on to develop diabetes. However, of those with impaired fasting glycaemia one in two people went on to develop diabetes over the same period.
Not everyone who has impaired fasting glycaemia develops diabetes in the future. By leading a healthy lifestyle you can keep your blood glucose level steady or reduce it. This means you can delay the development of diabetes or prevent it completely. If you know that your glucose level is raised, you have the chance to do something about it and prevent diabetes in the future.
Controlling your weight, eating a healthy, balanced diet and doing more physical activity can prevent your blood glucose level from increasing as time goes on. As well as leading a healthy lifestyle, ask your GP to check your blood glucose level once a year if you have impaired fasting glycaemia.
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- Seven million in the UK have prediabetes. Diabetes UK. www.diabetes.org.uk, accessed 28 December 2009
- Care Recommendation: Impaired glucose regulation (IGR)/ Non-diabetic hyperglycaemia (NDH)/ Prediabetes. Diabetes UK 2009. www.diabetes.org.uk
- Diabetes symptoms. Diabetes UK. www.diabetes.org.uk, accessed 28 December 2009
- Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford. Oxford University Press 2007: 404
- Glucose tests. Lab Tests Online. www.labtestsonline.org.uk, accessed 28 December 2009
- Managing prediabetes. Diabetes UK. www.diabetes.org.uk, accessed 28 December 2009
- Monitoring prediabetes. Diabetes UK. www.diabetes.org.uk, accessed 28 December 2009
- Preventing heart disease. British Heart Foundation. www.bhf.org.uk, accessed 28 December 2009