Patient information from BMJ

Diabetes type 1: what is it?

Last published:Feb 27, 2023

Type 1 diabetes is a long-term condition that usually starts in childhood or young adulthood, but which can also occur later in life. Taking insulin, eating a healthy diet, and staying active can help people with type 1 diabetes live a long and healthy life.

What is it?

If you have diabetes you have too much glucose in your blood. Glucose is a kind of sugar that your body uses for energy. But if too much of it builds up in your blood, it can make you ill. 

There are two main types of diabetes: type 1 and type 2. This information is for adults with type 1 diabetes and parents of children with this condition.

Type 1 diabetes usually starts in childhood, adolescence, or early adulthood, but it can also start later in adult life.

Everyone needs glucose energy, and everyone needs a hormone called insulin to keep their blood glucose at a healthy level. But when you have type 1 diabetes, your body stops making insulin or makes very little of it.

This kind of diabetes used to be called insulin-dependent diabetes, because it can be controlled by taking insulin.

Usually, type 1 diabetes is an autoimmune disease. This means that the cells in your immune system, which normally fight germs, attack some of your own cells by mistake. In type 1 diabetes, the immune system attacks the cells that make insulin.

Doctors don't know why this happens. It might be triggered by viruses, your genes, or a combination of factors. Sometimes people get type 1 diabetes without having an autoimmune problem, but this isn't common.

What are the symptoms?

If you or your child develops type 1 diabetes, the symptoms will probably start quite suddenly, over a few days or weeks. These might include:

• needing to urinate more often 

• feeling very thirsty 

• feeling very tired or weak 

• blurred vision 

• losing weight without trying. 

If you or your child has any of these symptoms, it’s important to see a doctor. The doctor will test your blood glucose level. 

What will happen to me?

Many children and adults with type 1 diabetes lead full, healthy lives by keeping their blood glucose level close to normal, eating healthily, and exercising regularly.

If you've had diabetes for a long time, you have an increased chance of extra health problems linked to your diabetes. Your eyes, kidneys, feet, and heart are the parts of your body most likely to be affected. Doctors call these problems complications.

Not everyone with diabetes gets complications. The closer your blood glucose is to normal, the less likely you are to get complications.

To detect any problems, you or your child will have regular check-ups. These may include checks of your

• blood glucose control

• eyes

• blood pressure

• cholesterol

• kidneys

• feet, and

• nerves.

It's also important that you stay up to date on vaccinations. This includes getting an annual flu vaccine.

Where to get more help

Diabetes support groups help many people cope with their illness and lead full lives. These groups can be especially helpful for parents of children with type 1 diabetes, who might find it a challenge to manage their child's diabetes at times.

You can ask your doctor or diabetes nurse about what groups are available in your area, or do a search for groups on the internet. One national organization that offers information and advice, as well as local support, is the American Diabetes Association (diabetes.org).

For more information on treatments for diabetes see our leaflet Diabetes type 1: what treatments work?