Testing for Diabetes
There are two forms of the disease: Type 1 or insulin-dependent diabetes, which usually starts in younger people, who will need regular insulin injections for life.
Type 2 diabetes is more common. It starts later in life and can usually be controlled by diet, exercise and tablets. However, the symptoms are much less obvious than those of Type 1 diabetes – as many as a million people may have diabetes and not know it. Tests to detect or monitor diabetes involve measuring your blood or urine glucose levels.
Diabetes is a disorder in which the body does not produce enough insulin (the hormone needed to extract glucose, the body’s main source of energy, from the blood). Or it may be resistant to insulin, causing raised blood glucose levels.
Who needs it
Healthchecks for older people will often include simple urine ‘dipstick’ tests for glucose, because if levels in the blood are raised, some often spills over into the urine. If the urine test is positive, your doctor will probably recommend a blood test. If you develop symptoms of diabetes, particularly thirst, frequent urination and weight loss, have your blood glucose tested.
Also talk to your doctor if you have symptoms such as loss of energy, itching around the genitals and blurred vision, especially if you are at risk of Type 2 diabetes. The risk steadily increases after the age of 40, and is higher in people who are overweight, in ethnic minority groups, and those with a family history of diabetes and women who had diabetes during pregnancy or gave birth to a baby weighing more than 4kg (9lb).
If you have diabetes, you will need regular blood glucose checks. You can monitor your own condition with finger-prick tests, backed up by blood samples drawn by your doctor from time to time.
How it is done
There are three types of blood test used to monitor diabetes: a random blood glucose test can be taken at any time; a fasting plasma glucose (FPG) test is taken from a blood sample usually drawn in the morning, before you have eaten; and an oral glucose tolerance test (OGTT) which comprises samples of blood and urine taken at intervals after drinking a glucose (sugar) solution.
For an OGTT, you will be instructed to fast for 8 hours (overnight) before the test and to avoid certain drugs, such as paracetamol and oral contraceptives, which can affect the results. People with diabetes may also have another type of blood test, called an HBA1c, which measures the amount of glucose in the red cells in the blood, to give an idea of the recent average glucose levels. This test is usually done every six to 12 months, to keep an eye on the overall control of your blood glucose. Diabetics having checks of HBA1c aim for a level of 7 per cent or less.
What the results mean
If your diabetes is typical, it can be diagnosed on any of the following blood test results:
- a random plasma glucose greater than 11.1mmol/L
- a fasting plasma glucose over 7.0mmol/L (or over 6.1mmol/L if the test is performed on whole blood)
- a plasma glucose concentration more than 11.1mmol/L 2 hours after an oral glucose tolerance test (OGTT).
If you do not have the typical symptoms, a second test will usually be done to confirm the dignosis. If levels on a random or fasting blood glucose test are high, but not high enough for a proper diagnosis to be made, you will probably be asked to undergo an OGTT.
If you are diagnosed with diabetes, you will need to have your blood glucose checked regularly, or check it yourself, with the aim of keeping your levels between 4 and 7mmol/L before meals and less than 10mmol/L 2 hours after meals.
Good control of your blood sugar level helps to reduce the risk of diabetic complications, which can include heart disease, blindness, stroke, kidney disease and nerve damage. Most diabetics manage their condition with very little trouble.