Impaired fasting glycaemia

Impaired fasting glycaemia is when blood glucose levels in your body are raised during periods without food (fasting), but aren’t high enough to mean that you have diabetes.

About impaired fasting glycaemia

Impaired fasting glycaemia is sometimes called pre-diabetes and is also known as impaired fasting glucose. It’s estimated that around seven million people in the UK have impaired fasting glycaemia.

If you have impaired fasting glycaemia, your body isn't able to regulate glucose as efficiently as it should. Glucose is a major source of energy for most cells in your body, including your brain. Carbohydrate foods, such as bread, pasta and rice, are broken down and turned into glucose when you eat them. Your liver can also produce glucose.

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 amount of glucose in your blood is automatically regulated by a hormone called insulin that is produced by your pancreas. If your pancreas doesn’t produce enough insulin or any at all, or the insulin that is produced doesn’t work properly (insulin resistance), the amount of glucose in your blood can become too high.

Blood glucose levels can be measured in a laboratory by testing a blood sample. This is usually done when you haven’t eaten for eight hours and is called a fasting blood glucose test. The amount of glucose in your blood changes throughout the day depending on what you're eating and drinking.

Symptoms of impaired fasting glycaemia

Impaired fasting glycaemia has no symptoms and can often go undiagnosed for years. Although there are no symptoms, many people diagnosed with impaired fasting glycaemia are overweight. Nine out of 10 people with impaired fasting glycaemia have high blood pressure, raised cholesterol levels or a family history of the condition.

Having impaired fasting glycaemia increases your risk of developing 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
  
• blurred vision
• pain or numbness in your hands or feet

These symptoms may be caused by problems other than type 2 diabetes. If you have any of these symptoms see your GP for advice.

Complications of impaired fasting glycaemia

If you have impaired fasting glycaemia, you’re at greater risk of developing type 2 diabetes and heart disease.

Causes of impaired fasting glycaemia

Impaired fasting glycaemia develops if your body becomes unable to control your glucose levels. Your body may not produce enough insulin or be able to use the insulin that it does produce properly. There are a number of factors that make you more likely to develop impaired fasting glycaemia. You may be at risk of getting impaired fasting glycaemia if you're black or South Asian and over 25, or if you're Caucasian and over 40, and if:

• one of your parents, brother or sister has type 2 diabetes
  
• you're overweight or you carry excess 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’re overweight
  
• you have had diabetes during pregnancy (gestational diabetes)

Diagnosis of impaired fasting glycaemia

Impaired fasting glycaemia is diagnosed by testing glucose levels in your blood. The first test you will have is called 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 6.1 millimoles per litre (mmol/l) and 6.9mmol/l, you have impaired fasting glycaemia.
  
• 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 your body isn’t able to control the amount of glucose in your blood.

Depending on the results of this test your GP may ask you to have a two-hour plasma glucose test (also known as an oral glucose tolerance test, or OGTT). If you have this test, your GP will ask you not to eat anything for 12 hours before the blood sample is taken. After the blood sample is taken, your GP will ask you to swallow a drink containing 75g 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

Impaired fasting glycaemia 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 impaired fasting glycaemia level once, you should have regular fasting glucose tests every year.

Self-help

People with impaired fasting glycaemia 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. The following are examples of how you can do this.

• Eat a healthy balanced diet that is low in fat, salt and sugar, and high in fibre with plenty of fruit and vegetables.
  
• Lose any excess weight if you're overweight and make sure your weight stays within the recommended range for your height. This can help your body regulate insulin better. Use our body mass index calculator to work out if you’re a healthy weight for your height.
  
• Improve your fitness by doing 150 minutes (two and a half hours) of moderate intensity exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes of exercise on at least five days each week. Alternatively, you can do 75 minutes of vigorous intensity activity twice a week.
• Drink no more than three or four units of alcohol a day if you’re a man, or two or three units a day if you’re a woman.

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

Produced by Dylan Merkett, Bupa Health Information Team, May 2012.

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