Impaired fasting glycaemia

Published by Bupa's Health Information Team, April 2010.

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

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.

Symptoms of impaired fasting glycaemia

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.

Complications of impaired fasting glycaemia

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.

Causes of impaired fasting glycaemia

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

Diagnosis of impaired fasting glycaemia

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.

Treatment of impaired fasting glycaemia

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.

Self-help

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 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes on at least five days each week. Alternatively, you can do 75 minutes of vigorous intensity activity.

As well as taking the steps above you can also reduce your risk of heart disease and stroke by giving up smoking.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.