Tests for Glucose (Sugar) and HBA1c

Urine test for glucose

Urine does not normally contain glucose. If the blood glucose level goes above a certain level, then some glucose 'spills' through the kidneys into the urine. A simple 'dipstick' test can detect glucose in a sample of urine. If you have glucose in your urine, you are likely to have diabetes.

However, some people have kidneys that are more 'leaky', and glucose may leak into urine with a normal blood level. Therefore, if your urine contains any glucose you should have a blood test to measure the blood level of glucose to confirm, or rule out, diabetes.

Blood tests for glucose

Random blood glucose level
A sample of blood taken at any time can be a useful test if diabetes is suspected. A level of 11.1 mmol/l or more in the blood sample indicates that you have diabetes.

Fasting blood glucose level
A glucose level below 11.1 mmol/l on a random blood sample does not rule out diabetes. A blood test taken in the morning before you eat anything (after an 'overnight fast') is a more accurate test. A level of 7.0 mmol/l or more after an overnight fast indicates that you have diabetes.

Oral glucose tolerance test
This test may be done if the diagnosis of diabetes is in doubt. For this test, you fast overnight. In the morning you are given a drink which contains 75g of glucose. A blood sample is taken two hours later. Normally, your body should be able to deal with the glucose and your blood level should not go too high. A glucose level of 11.1 mmol/l or more in the blood sample taken after two hours indicates that you have diabetes.

Home monitoring
A drop of blood from a 'finger prick' is placed on a test strip which has a chemical impregnated which reacts with glucose. By using a colour chart, or a small glucose meter machine, the blood level of glucose can be measured quickly.

The HbA1c blood test

If you have diabetes, your HbA1c level may be done every 2-6 months by your doctor or nurse. This test measures your recent average blood glucose level. The test measures a part of the red blood cells. Glucose in the blood attaches to part of the red blood cells. This part can be measured and gives a good indication of your average blood glucose over the last 2-3 months.

Treatment aims to lower your HbA1c to below a target level which is usually agreed between you and your doctor. The target level is usually somewhere between 6.5% and 7.5%. If your HbA1c is above your target level then you may be advised to 'step up' treatment to keep your blood glucose level down. (For example, by increasing the dose of medication, improving your diet, etc.)

© EMIS and PIP 2006   Updated: February 2006