Glucose tolerance test

A glucose tolerance test takes 2 hours. You will be required to fast (no food) from the night before the test. A blood sample will be taken and you will then be given a stronger glucose solution to drink. You will be asked not to smoke, eat or drink anything except some water. Another blood sample will be taken 2 hours later. If the amount of glucose in the blood rises above a certain level diabetes is diagnosed.

Glucose tolerance tests are used when the results of the fasting blood glucose are borderline. They are also used to diagnose diabetes in pregnancy (gestational diabetes).