Before answering the question “how do you test for diabetes?”, it is important to understand what diabetes is. 

Diabetes is a condition in which the body has too much glucose, a type of sugar in the blood. 

Typically, the body produces a hormone known as insulin that moves glucose from the bloodstream to the body’s cells. However, diabetes affects the body’s ability to produce or use insulin, leading to a build up of glucose in the blood that can lead to health complications in both the long and short term.

That is why it is important to test for diabetes when it is first suspected. The earlier diabetes is detected, the easier it is to manage (and in some cases related to Type 2 Diabetes, even prevented).

Typically, your doctor will order one or more diabetes tests if you exhibit the following symptoms:

  • Being more thirsty than usual
  • Passing more urine
  • Feeling tired and lethargic
  • Always feeling hungry
  • Having cuts that heal slowly
  • Itching, skin infections
  • Blurred vision
  • Unexplained weight loss (this is for type 1 diabetes)
  • Gradually putting on weight (this is for type 2 diabetes)
  • Mood swings
  • Headaches
  • Feeling dizzy
  • Leg cramps

What kinds of tests for diabetes are there?

There are multiple diabetes tests available in order to accurately measure the amount of glucose in the blood and effectively determine whether or not diabetes is present in the patient. 

The Haemoglobin A1c (HbA1c) Test

As glucose circulates in the blood, it can bind to haemoglobin (the protein that helps red blood cells carry oxygen), resulting in a combination known as HbA1c. As a result, higher glucose results in higher HbA1c levels.

The HbA1c test is a blood test in which the goal is to measure the amount of HbA1c to determine the levels of glucose. If the person is subsequently diagnosed with diabetes, it is required that they repeat the test every 3-6 months in order to monitor HbA1c levels as a helpful guide to reduce risk of complications.

This test does not require preparation beforehand and can be conducted at any time. However, the patient may be asked to fast (e.g. no food or fluid except water for eight hours) beforehand.

Oral Glucose Tolerance Testing (OGTT)

This test analyses how effectively the body’s cells are able to absorb glucose in order to diagnose type 2 diabetes, as well as gestational diabetes (a type of diabetes that develops during pregnancy).

This test involves the person being given a bottle of glucose to ingest in a 5 minute period. After that, multiple blood tests are conducted after one hour, and then after another hour, to monitor the changes in your body’s glucose levels. 

Other tests for diabetes include fasting blood glucose and random blood glucose tests. Fasting blood glucose test measures blood glucose after you have not eaten for 8 to 12 hours hours while random blood glucose test measures the blood glucose regardless of when you last ate.

How is diabetes diagnosed?

The only way to formally diagnose diabetes is with a blood test. Once the blood has been extracted from the vein, it is sent to a pathology lab for analysis.

When is diabetes confirmed?

Diabetes is confirmed when one or more of the following conditions are met:

  • Diabetes symptoms are present and: 
    • fasting blood test result is at or above 7.0mmol/L, or 
    • a random blood test result is at or above 11.1mmol/L
  • HbA1c blood test result is at or above 6.5% (48 mmol/mol)
  • There have been no symptoms and: 
    • fasting blood test result is at or above 7.0mmol/L, or 
    • a random blood test result is at or above 11.1mmol/L

Can diabetes be diagnosed with a blood glucose monitor or urine test?

A diabetes diagnosis cannot be made until the person’s blood is analysed by a pathology lab. While a blood glucose monitor or a urine test can uncover trends in the person’s glucose levels, they can’t be used to diagnose diabetes on their own.

How will my doctor know which type of diabetes it is?

It can sometimes be difficult to distinguish between type 1 diabetes and type 2 diabetes in adults. Your doctor will make an informed decision based on the history and severity of your symptoms, then use further blood tests to confirm whether or not you have type 1 diabetes (if type 1 diabetes is suspected).

Your doctor may also check for ketones in your blood or urine which can help with the diagnosis. Ketones can be a sign that you lack insulin (and is usually associated with rapid weight loss). There are other tests that can help to determine the type of diabetes, such as insulin levels and certain antibodies in the blood, but these can take several weeks to confirm.

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 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 a glucose tolerance test (GTT).

How can the Life! program help me prevent type 2 diabetes?

The Life! program offers a health check – a 2-minute survey that assesses your risk for type 2 diabetes. It also offers you a wide range of resources to help you adopt a lifestyle that will help prevent type 2 diabetes.

Life! is a free healthy lifestyle program that helps you improve your eating habits, increase your physical activity and manage stress. You can choose from a group course or the Telephone Health Coaching service. 

Our experienced health professionals will help you make small changes to your lifestyle so that you can achieve your health goals and reduce your risk of type 2 diabetes, heart disease and stroke.

Life! is funded by the Victorian government and managed by Diabetes Victoria. You can check your eligibility for the program here.

Take the health check



Elleni Kaias, Accredited Practicing Dietitian | Primary Care Engagement Lead

Kristie Cocotis, Head of Prevention and Health Promotion

Sarah Dubé, Strategy and Engagement Lead

Ria Cheripuram, Digital Communications Officer

Tegan Kohlman, Communications and Social Marketing Officer