What is type 1 diabetes?

What is

Type 1 diabetes (T1D) is a lifelong autoimmune disease that usually occurs in childhood but can be diagnosed at any age.

T1D is caused by the immune system (which is meant to protect you from foreign bodies such as viruses and bacteria) mistakenly targeting cells that are part of a person’s own body.

In type 1 diabetes, the immune system attacks the cells in our pancreas that produce insulin, called beta cells. Insulin helps the body convert glucose (sugar) from food into fuel. Without insulin, glucose can build up in the bloodstream in life-threatening amounts.

Since people with T1D cannot produce insulin naturally, they must take it either through daily injections or from an insulin pump.


Type 1 diabetes affects over 130,000 people in Australia alone. Eight more Australians are diagnosed each day.


How is type 1 diabetes diagnosed?

Many people with T1D start their type 1 diabetes diagnosis journey when they visit their GP after noticing something isn’t quite right. They may be experiencing some of the common symptoms of type 1 diabetes, including excessive thirst, frequent urination, tiredness and weight loss. People who have had their type 1 diabetes go unnoticed and untreated for longer could be experiencing a serious condition called diabetic ketoacidosis (DKA), which requires urgent treatment.

GPs and other healthcare providers can carry out several tests for a type 1 diabetes diagnosis. The first check is often a random blood glucose test, done via a finger prick.

Other tests to diagnose type 1 diabetes include the options below.


Random blood glucose test

The quickest and often the first option for testing for T1D is a random glucose test measuring a patient’s current blood sugar.


Fasting blood glucose test

This is a blood test typically conducted in the morning after fasting overnight. The fasting helps give doctors a clear look at how the body manages blood sugar levels without the impact of food intake.


Oral glucose tolerance test

After fasting and having an initial blood test, people drink a sugary drink and then have their blood sugar tested over the course of approximately two hours. This shows the benchmark sugar level without outside influences and later measures how the body responds to carbohydrate (sugar) intake.


Glycated haemoglobin (HbA1c) test

The most comprehensive test is the haemoglobin A1c test. This blood test shows the average blood-sugar level for the past two or three months.

Learn more about HbA1c and how it’s tested



While most tests check for antibodies, this test measures how much C-peptide is in a person’s blood. Peptide levels typically mirror insulin levels in the body. Low levels of C-peptide and insulin can point to T1D.


Insulinoma-associated-2 autoantibodies (IA-2A)

This test looks for antibodies mounted against a specific enzyme in beta cells. Both the IA-2A and GADA tests (see below) are common T1D antibody tests.


Zinc transporter 8 (ZnT8Ab)

Looks at antibodies targeting an enzyme that is specific to beta cells.


Islet cell cytoplasmic autoantibodies (ICA)

This test identifies a type of islet cell antibodies present in up to 80% of people with T1D.


Glutamic acid decarboxylase autoantibodies (GADA or Anti-GAD)

This test looks for antibodies built against a specific enzyme in the insulin-producing pancreatic beta cells.

What other types of diabetes are there? 

Type 2 diabetes

People with type 2 diabetes develop insulin resistance, meaning their body doesn’t use insulin as well as it should. In later stages of type 2 diabetes, people may also not produce enough insulin.

Type 2 diabetes is caused by a combination of genetics and lifestyle factors, such as being overweight or having a sedentary lifestyle.

Type 2 diabetes can often be managed by diet changes, exercise and medication. However, it is a progressive condition and some people may need to inject insulin in later stages of the disease.


Some people who were initially diagnosed as having type 2 diabetes actually have latent autoimmune diabetes of adults (LADA).  This is sometimes referred to as type 1.5 diabetes.

People with LADA have features of both type 1 and type 2 diabetes in that their immune system attacks the cells of the pancreas that produce insulin, but they may also have insulin resistance. The destruction of the insulin producing cells is much slower in LADA than in type 1 diabetes.

For some people, LADA can be managed with diet, exercise and medication. However, most people with LADA will require insulin therapy within the first year.

Gestational diabetes

Gestational diabetes refers to diabetes that is first detected during pregnancy. Pregnant women produce large amounts of hormones such as oestrogen and progesterone, which can cause the body to become resistant to the effects of insulin.

By the time a woman reaches the end of the third trimester, her insulin requirements have tripled. If the pancreas is unable to match this increased demand, blood glucose levels start to rise. In general, blood glucose returns to normal after pregnancy. However, women diagnosed with this type of diabetes are at significantly higher risk of developing type 2 diabetes later in life.

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