Diabetes is not just one condition. The two main types — type 1 and type 2 diabetes — both cause high blood glucose, but they develop for different reasons.
In type 1 diabetes, the immune system attacks the cells in the pancreas that make insulin. As a result, the body produces little or no insulin and needs insulin replacement to survive.
Type 2 diabetes develops differently. The body becomes less responsive to insulin, known as insulin resistance, and over time the pancreas may not produce enough insulin to keep blood glucose levels under control.
The symptoms can overlap, but the way the conditions develop, how they are treated and whether they can be prevented are quite different
Key difference
- Both types can cause high blood glucose and some of the same symptoms.
- Type 1 often develops quickly. Type 2 may develop gradually or cause no obvious symptoms.
- Everyone with type 1 needs insulin. Some people with type 2 also need it.
- Type 1 can’t currently be prevented. Type 2 can sometimes be prevented or delayed.
- Either type can occur at different ages, so age alone doesn’t decide the type.
Type 1 vs Type 2 Diabetes at a Glance
| Feature | Type 1 Diabetes | Type 2 Diabetes |
|---|---|---|
| Cause | An autoimmune reaction destroys the insulin-producing cells in the pancreas | The body becomes resistant to insulin and, over time, may not produce enough |
| Onset | Can develop at any age, but is more common in children, teenagers and young adults | More common in adults, but can also develop in younger people and children |
| Symptoms | Often appear quickly and can become severe | May develop gradually, and some people have no symptoms for years |
| Treatment | Insulin is needed from diagnosis | Lifestyle changes and medicines; some people eventually need insulin |
| Testing | Blood glucose tests, with other tests sometimes used to identify the type | Blood glucose tests such as fasting glucose, HbA1c or an oral glucose tolerance test |
| Prevention | Cannot currently be prevented | For some people, the onset can be prevented or delayed through lifestyle changes |
What Is Type 1 Diabetes?
Type 1 diabetes is an autoimmune condition. The immune system mistakenly attacks the beta cells in the pancreas, the cells responsible for producing insulin.
As these cells are destroyed, the body can no longer make the insulin it needs. Without enough insulin, glucose cannot move effectively from the bloodstream into cells, causing blood glucose levels to rise.
Type 1 diabetes can develop at any age. It is often associated with younger people, but adults can develop it too. Healthdirect notes that the most common age for diagnosis is between 10 and 14 years, although type 1 can occur outside this age range.
The exact reason why the immune system starts attacking these cells is not fully understood. Genetics appear to play a role, along with possible environmental triggers.
Importantly, type 1 diabetes is not caused by eating too much sugar or by a person’s lifestyle.
What Causes Type 1 Diabetes?
Why the immune system starts attacking the insulin-producing cells isn’t fully understood. Genetics seem to play a role, along with possible environmental triggers. Type 1 diabetes isn’t caused by eating too much sugar or by lifestyle.
It can develop at any age. It’s often linked with children and teenagers, and diagnosis most often happens between 10 and 14 years, but adults can develop it too.
What Is Type 2 Diabetes?
Type 2 diabetes develops when the body does not respond properly to insulin. This is called insulin resistance.
At first, the pancreas may produce more insulin to try to compensate. Over time, however, it may not be able to produce enough insulin to keep blood glucose within a healthy range.
Type 2 diabetes is much more common than type 1 diabetes. Diabetes Australia estimates that it accounts for around 85–90% of diabetes cases in Australia.
Age, family history, genetics, physical activity, diet and other factors can all contribute to the risk of type 2 diabetes. Having a higher body weight can also increase risk, but type 2 diabetes can affect people of different body sizes.
Unlike type 1, some cases of type 2 diabetes can be prevented or delayed. This does not mean that everyone who develops type 2 diabetes could have prevented it. Genetics, age and other factors also matter.
What Causes Type 2 Diabetes?
There’s no single cause. Age, family history, genetics, physical activity, diet and body weight all contribute to risk. Higher body weight raises risk, but type 2 diabetes affects people of many body sizes. Not everyone who develops it could have prevented it.
Symptoms of Type 1 vs Type 2 Diabetes
Both types can cause the same symptoms, because both lead to high blood glucose:
- Feeling very thirsty
- Passing urine more often
- Feeling tired
- Increased hunger
- Blurred vision
- Unexplained weight loss
The main difference is how quickly they appear.
Type 1 symptoms
Symptoms usually develop over days or weeks in someone who was previously well, and can become severe. Some people are first diagnosed when they develop diabetic ketoacidosis (DKA). This happens when the body doesn’t have enough insulin and starts breaking down fat for energy, producing ketones. DKA symptoms include nausea, vomiting, abdominal pain, dehydration, fast breathing and a fruity or acetone-like smell on the breath. DKA needs urgent medical treatment.
Type 2 Symptoms
Symptoms usually develop gradually, and many people have none for years. Doctors often find it through a blood test or screening. Our guide covers the early signs of type 2 diabetes and who should be tested.
Age and body weight don’t reliably show which type someone has. A higher body weight doesn’t rule out type 1.
How Is Type 1 Diabetes Diagnosed?
Both type 1 and type 2 diabetes are diagnosed by checking blood glucose levels. Tests may include a fasting blood glucose test, random blood glucose test, HbA1c or an oral glucose tolerance test, depending on the circumstances.
The blood glucose result confirms that diabetes is present, but it does not always tell the doctor which type a person has.
If type 1 diabetes is suspected, additional tests may be used to look for signs of the autoimmune process, including diabetes-related autoantibodies. A C-peptide test may also help assess how much insulin the pancreas is producing.
This distinction matters because someone who actually has type 1 diabetes needs insulin replacement, even if they are initially thought to have type 2 diabetes.
How Are Type 1 and Type 2 Diabetes Treated?
Type 1 diabetes treatment
People with type 1 need insulin replacement because the body can’t make enough of its own. Insulin can be given by injection, pen or pump. They also need to monitor blood glucose and learn how food, activity, illness and insulin affect their levels. Healthy eating and regular activity stay important, but they don’t replace insulin.
Type 2 diabetes treatment
Treatment depends on blood glucose levels, overall health and how the condition responds. It may include:
- Changes to eating habits
- Regular physical activity (see our guide to exercising safely with diabetes)
- Weight management where appropriate
- Medicines to lower blood glucose
- Other medicines for related conditions such as high blood pressure or cholesterol
- Insulin, when needed
Some people with type 2 diabetes reach remission. See what diabetes remission means.
Does type 2 diabetes need insulin?
Not always. Some people manage type 2 with lifestyle changes and non-insulin medicines. Others eventually need insulin because the pancreas makes less over time or other treatments are no longer enough. Needing insulin doesn’t mean someone with type 2 has developed type 1. They remain different conditions.
Can Type 1 or Type 2 Diabetes Be Prevented?
Can type 1 diabetes be prevented?
At present, there’s no established way to prevent it. Because it’s autoimmune, healthy eating and exercise don’t stop the immune system attacking the insulin-producing cells. Research into identifying and delaying type 1 is ongoing, but there’s no routine lifestyle-based prevention.
Can type 2 diabetes be prevented?
For some people, changes to physical activity, eating habits and weight can prevent or delay type 2. That doesn’t mean everyone who develops it could have prevented it. Genetics, family history and age also matter. Australia’s AUSDRISK tool looks at several of these factors to estimate risk over five years.
Type 1 Diabetes in Adults
Type 1 is sometimes thought of as a childhood condition, but adults can develop it too. Diagnosis can be harder because diabetes in an adult is often assumed to be type 2.
Some adults have a slower-onset autoimmune diabetes called latent autoimmune diabetes in adults (LADA), which can look like type 2 at first. If the picture doesn’t fit, for example if someone needs insulin soon after diagnosis, a doctor may check whether another type is involved.
When Should You See a GP?
Speak with a GP if you:
- Have symptoms that could be related to diabetes
- Have unexplained weight loss, increased thirst or frequent urination
- Have several risk factors for type 2 diabetes
- Have been told you have high blood glucose
- Aren’t sure whether you have type 1 or type 2
A GP can assess your symptoms and risk factors and arrange blood tests. You can book an online GP consultation to talk through your symptoms or concerns.
If symptoms come on suddenly and you feel very unwell, particularly with vomiting, abdominal pain, difficulty breathing, severe dehydration or confusion, seek urgent medical care or call 000. These can be signs of DKA. [Reviewer to confirm wording, and keep it identical across the cluster.]
Frequently Asked Questions (FAQ)
What's the difference between juvenile diabetes and adult-onset diabetes?
These are older terms and can mislead. Type 1 can develop at any age, and type 2 can occur in children and younger adults. The type depends on how the diabetes develops, not on the person’s age.
Is gestational diabetes the same as type 2 diabetes?
No. Gestational diabetes develops during pregnancy. Having it raises the chance of type 2 diabetes later in life.
Can you have type 1 and type 2 diabetes at the same time?
It is possible for a person to have features of both autoimmune diabetes and insulin resistance, but Type 1 and Type 2 diabetes remain distinct conditions. A doctor may need additional testing when the type of diabetes is unclear.
Which diabetes is more common?
Type 2. In Diabetes Australia’s 2023 snapshot of National Diabetes Services Scheme registrations, about 87% were type 2, 9% type 1 and 3% gestational. Registrations likely undercount the true numbers.
Is Type 1 Diabetes Genetic?
Genetics can increase the likelihood of developing Type 1 diabetes, but having a family history does not mean that someone will definitely develop it. Other factors are also thought to be involved.
What Happens If Type 1 Diabetes Is Not Treated?
Without enough insulin, blood glucose can rise rapidly and the body may begin breaking down fat for energy, producing ketones. This can lead to diabetic ketoacidosis (DKA), a serious condition requiring urgent medical treatment.
Can You Have Type 1 Diabetes Without Knowing It?
Type 1 diabetes usually causes noticeable symptoms that develop over a relatively short period. However, symptoms can vary, and some people are diagnosed after becoming seriously unwell. If you have symptoms such as excessive thirst, frequent urination, unexplained weight loss or extreme tiredness, see a GP promptly.
Conclusion
The type of diabetes decides how it’s treated and whether it can be prevented. Type 1 always needs insulin and can’t currently be prevented. Type 2 has more treatment options and, for some people, can be delayed or prevented.
If you have symptoms or are worried about your risk, a GP can arrange testing and help work out what’s causing the changes.
HelloGP - Disclaimer
This article is for general information only and does not replace professional medical advice. Telehealth is not suitable for emergencies. If you have an emergency or are at immediate risk, call 000 or visit your nearest emergency department.