Diagnosis

How diabetes is diagnosed

Most people with type 1 diabetes and many with type 2 diabetes will present with symptoms of diabetes. However some people with type 2 diabetes may have no symptoms at all.

Diabetes is diagnosed when:

• Symptoms of diabetes are present and a random (non fasting) blood glucose level is equal to or greater than 11.1mmol/L.
• A fasting blood glucose level is equal to or greater than 7mmol/L.
• 2 hour blood glucose level is equal to or greater than 11.1mmol/L during an oral glucose test.

What if my blood test is not normal, but not diabetes either?

Some people will have a fasting blood level that is above the normal range, but not high enough to be diagnosed as diabetes. For example, a fasting blood glucose level that is between 5.5mmol/L and 6.9mmol/L is above the normal range but does not confirm or rule out diabetes or pre-diabetes. In this situation your doctor should order an oral glucose tolerance test (OGTT).

Oral Glucose Tolerance Test (OGTT)

What is an OGTT?

An OGTT involves a blood test taken from a vein, usually the arm, at a pathology laberatory.

What you need to do before a OGTT test

• Three days before you should have an adequate carbohydrate intake (greater than 150g per day). Examples of carbohydrate include bread, potato, fruit, rice, pasta and milk.
• You will need to fast for eight hours before the test. This is usually done overnight.
• A fasting blood glucose test is taken. You are then given a sweet drink that contains 75g of glucose.
• Your blood glucose level is checked at one hour and again at two hours after the glucose drink.

You should discuss your results with your doctor or health care team.

The National Diabetes Services Scheme (NDSS) is an initiative of the Australian Government administered with the assistance of Diabetes Australia.