Glucose (blood sugar levels) test

A fasting glucose test is the benchmark for diagnosing diabetes. (Turn to the previous page for more information about diabetes.)

What’s involved? “Glucose is measured in the blood, so your doctor will take a blood sample,” says Dr Thistlethwaite. “Usually you will have to fast for eight to 10 hours beforehand.”

What next? High levels may suggest an increased risk.

Your doctor may ask for further investigation.