Causes of type 1 diabetes | Breakthrough T1D

What causes type 1 diabetes?

In a nutshell, it starts because our immune system – which usually protects us against illness and infection – attacks and destroys insulin-producing cells in the pancreas. In turn, this leads to insulin deficiency and type 1 diabetes.

But why this process happens is a bit more complex. Is type 1 diabetes genetic? Or are there other reasons you might develop it? Experts agree that genes pave the way for the condition to develop, but environmental factors contribute to type 1 diabetes risk factors, too.

And where you live, how much sunlight you get, the food you eat – it may all affect your chance of developing type 1 diabetes, but scientists can’t definitively say why, or by how much. There’s still a lot about type 1 diabetes we don’t know, but the good news is, we’re finding out more every day.

Is type 1 diabetes genetic?

Good question. We know that the genes you inherit from our parents play a part in the development of type 1 diabetes (T1D) – but the condition develops in stages in the body, and it can take years for symptoms to show up.

And it’s not any one gene that ‘switches’ on the condition; rather, experts believe a collection of HLA genes have the biggest influence. Your particular genetic roadmap may have genes that put you at greater risk of T1D, or have other genes that protect you from it.

While it was once thought that Caucasians were at a higher risk of being diagnosed with T1D, this seems to be changing. Minority populations are now being diagnosed at an increasing rate, meaning that the group of people living with T1D around the world is much more diverse. You can see the global impact of T1D at the T1D Index.

But even if you have genes that put you at greater risk of getting T1D, it’s not a given that you’d develop it. That’s why we sometimes see identical twins with the same genes, and one gets it and the other doesn’t. This is where environmental factors come in.

Type 1 diabetes and your family

Firstly, 90% of people who develop type 1 diabetes don’t have a family history of it. But if you have a parent, brother or sister with it, you have a higher chance of developing type 1 diabetes than someone who doesn’t have a relative with the condition.

Your age also comes into play in type 1 diabetes risk factors. More than 60% of people diagnosed with type 1 diabetes are under the age of 25.

Although type 1 diabetes can appear at any age, it’s usually diagnosed in childhood or the early teen years, with ‘peak’ ages for diagnosis between the ages of four to seven, then 10 to 14.

~145000

Australians are living with T1D

90%+

of people living with T1D have no family history of the condition

60%

of people diagnosed with T1D are under the age of 25

Environmental risk factors for type 1 diabetes

Most people, even if they have T1D risk factors, just don’t develop the condition, so researchers have looked into environmental risk factors that may trigger type 1 diabetes as well.

Believe it or not, cold weather – and how far you live from the equator – could all influence whether you develop T1D.

Catching different types of viruses may also put you at a higher risk of T1D, too.

Viral infections

Lots of evidence suggests there’s a potential link between exposure to certain viruses and developing T1D.

The main viral infections considered to raise your risk include rubella, mumps and enterovirus (the most famous enterovirus is polio, but generally these types of viruses aren’t serious and just present like a common cold or flu). We also know that infection with rubella during pregnancy is associated with an increased risk of diabetes in the baby.

And what about Covid? Well, in the last two years, several studies have also explored a possible link between Covid-19 and new-onset T1D in children. In Australia, we also saw higher cases of T1D during Covid – but further research is required to assess whether Covid truly has an influence over diabetes diagnoses.

Climate and geography

Where you live and the kind of weather you’re exposed to could play a role in the development of T1D.

Scientists aren’t sure why, but research shows that cases of T1D are about 10 times higher in high-income countries compared to low-income countries.

Also, scientists have found more people are diagnosed with diabetes in winter. Similarly, studies show you’re more likely to develop diabetes if you live in a cold climate, at a high altitude or don’t get a lot of sunshine. Not surprisingly, it’s very common in Northern Europe – Finland and Sweden have very high rates of T1D.

Early life and type 1 diabetes risk factors

If you’re a parent with T1D you might worry about what’s ahead for your child. Or if you’re a child whose parent has T1D, you may wonder if you’re going to develop it. It’s really hard to say – and there isn’t anything you can do to prevent it, either.

For many years, researchers have scrutinised risk factors for T1D in children, and tried to isolate why some children might develop the condition while others don’t.

There is some research to suggest that a pregnant mother who picks up an enterovirus during pregnancy could raise her baby’s risk of developing T1D down the track, but results aren’t really conclusive.

Diet and lifestyle are not factors in the onset of T1D, unlike with type 2 diabetes.

Conclusion

While there’s a huge amount of research around T1D risk factors, it seems that both genes and environment have a role to play.

And while countless studies into T1D haven’t yet led to a cure, scientists learn new things every day about the condition. Our growing knowledge continues to pave the way for treatments that make it easy to manage your glucose levels and live a normal life.