Urine testing involves holding a test strip under a stream of urine for a few seconds and comparing the colour change on the strip, after a set amount of time, with the chart on the strip container. This shows the percentage of glucose in the urine, where 0 per cent is the ideal.

If you have been advised to test your urine for glucose it is best to test it in the morning before your breakfast. Empty your bladder when you get up, then test a sample passed 30 minutes later. Tests done at this time should be negative. You can also test two to three hours after a meal, when your blood glucose will have been at its highest.

Urine testing gives a less accurate picture of your blood glucose than blood testing, but your doctor may still feel that it is suitable for you. It is less accurate because there is usually no glucose in your urine unless the glucose levels has risen to 10mmol/l or above, which is considered quite high. Also, it does not give you an indication of what your blood glucose level is at the time you test, because the urine you are testing may have been produced several hours before you test. Urine tests also cannot tell you if your blood glucose is too low – which is important for people on insulin or certain tablets.

Some people get glucose in their urine at lower levels. They are said to have a 'low renal threshold' for glucose. Older people may develop a high renal threshold, when glucose does not appear in the urine until the level in the blood is much higher than 10mmol/l. High or low renal thresholds will cause confusion if you are monitoring your diabetes with urine tests.