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Impaired fasting glycaemia

This factsheet is for people whose blood test has shown a marginally high fasting glucose (blood sugar) level or who would like information about impaired fasting glycaemia.

Impaired fasting glycaemia (IFG) means that your body isn't able to regulate glucose as efficiently as it should.

  • About impaired fasting glycaemia
  • Complications
  • Causes
  • Diagnosis
  • Treatment
  • Further information
  • Sources
  • Related topics

About impaired fasting glycaemia

Glucose enters the blood from your intestines, where it's absorbed from food and drinks as a natural part of digestion. When glucose reaches your body tissues, such as muscle, it's made available to cells where it is needed for energy by the hormone insulin. Insulin regulates the level of glucose in the blood so that it doesn't go too high or too low.

What is the normal range for blood glucose?

Blood glucose concentrations change throughout the day. They are typically higher after eating and lower during fasting. A fasting blood glucose level lower than 6mmol/l is normal. A fasting blood glucose of 7mmol/l or higher may indicate 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 below 7mmol/l but above 6mmol/l you may have IFG or impaired glucose tolerance (IGT). IFG and IGT are not diabetes but suggest that your body is not converting glucose to energy as efficiently as it should.

For the range of blood glucose concentrations associated with IFG, see Diagnosis.


Some people with IFG will go on to develop type 2 diabetes. Others may develop diabetes only if they don't take steps to reduce the chances of this happening (see Self-help). Diabetes is 10 to 20 times more likely in those with IGT or IFG.

Since IFG can be an early sign of type 2 diabetes you should watch out for the symptoms of the condition. They can include:

  • thirst
  • passing more urine than normal
  • unintentional weight loss or weight gain
  • re-occurring infections
  • blurring of vision

If you experience any of these symptoms, you should talk to your GP. For more information about type 2 diabetes, please see Related topics.

People with IFG also have a slightly increased risk of heart disease and stroke.


IFG is caused by the body's inability to regulate glucose levels correctly. Insulin production may be reduced and/or cells may be resistant to insulin so blood glucose levels are higher than normal.

If you are overweight and do not take regular exercise, your risk of developing IFG and IGT is increased.


IFG and diabetes are diagnosed by testing glucose levels in the blood. There are two basic blood tests.

For a fasting plasma glucose test you will be asked not to eat anything for eight to 10 hours before your doctor takes a blood sample.

With a two-hour plasma glucose test (also known as an oral glucose tolerance test) you are also asked not to eat anything. A blood test is taken and then you will be asked to take a drink containing a known amount of glucose. Further blood samples may be taken during the test and a final test is taken two hours after to see how your body deals with the glucose.

A fasting blood glucose level of between 6.1 and 6.9mmol/l indicates IFG. This is above the normal range but lower than the level that may indicate diabetes. Your result does not mean that you have diabetes or that you are at immediate risk of the problems associated with diabetes. IFG can be an early warning that type 2 diabetes may develop. If your fasting blood glucose level is within this range, your GP may offer an oral glucose tolerance test to rule out a diagnosis of diabetes.


IFG does not need medical treatment, but if you have had an impaired fasting glucose level once, it's advisable to have regular fasting glucose tests every few years.


As people with IFG have a greater risk of developing type 2 diabetes and are at a slightly increased risk of heart disease and stroke, it is important that you minimise your chances of developing these conditions. You should aim to reach and maintain 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 includes plenty of fruit and vegetables
  • 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 this you can also reduce your risk of heart disease and stroke by:

  • maintaining normal blood pressure levels - if your blood pressure is raised you may need to review your lifestyle to reduce stress (your doctor can advise you on diet and exercise) and sometimes medicines to lower your blood pressure may be needed
  • making sure that your cholesterol is kept low - your doctor will be able to advise you on diet and any medicines to help you reduce high cholesterol levels
  • increasing the amount of oily fish in your diet
  • giving up smoking
  • reducing the amount of alcohol you drink

Further information

Diabetes UK


  • Diabetes Type 2 - blood glucose management. NHS Library for Health. Clinical Knowledge Summaries. www.cks.library.nhs.uk, accessed 10 December 2007
  • Insulin resistance and pre-diabetes. National Diabetes Information Clearinghouse (NDIC). http://diabetes.niddk.nih.gov, accessed 10 December 2007
  • Definition and diagnosis of diabetes mellitus and intermediate hyperglycaemia. Report of a WHO/IDF consultation. World Health Organisation, 2006. www.who.int
  • Impaired glucose tolerance and impaired fasting glycaemia. Diabetes UK. www.diabetes.org.uk, accessed 10 December 2007
  • Magliano DJ et al. Glucose indices, health behaviours and incidence of diabetes in Australia: the AusDiab study. Diabetes Care 2007 Nov 5; Epub ahead of print
  • Angina. NHS Library for Health. Clinical Knowledge Summaries. www.cks.library.nhs.uk, accessed 10 December 2007

Related topics

  • Giving up smoking
  • Healthy weight for adults
  • High blood pressure
  • High cholesterol
  • Looking after your heart
  • Physical activity
  • Sensible drinking
  • Stress
  • Stress at work
  • Stroke
  • Type 2 diabetes