Type 1 diabetes

9th September, 2020 • 14 min read

What is type 1 diabetes?

Diabetes is a lifelong condition that causes a person's blood glucose (sugar) level to become too high. It’s also known as diabetes mellitus, and there are 2 main types: type 1 and type 2.

Type 1 diabetes is often called insulin-dependent diabetes. It’s also sometimes known as juvenile diabetes or early-onset diabetes because it often develops before the age of 40, usually during the teenage years.

When to get medical help

In some cases, type 1 diabetes can cause complications that need emergency medical treatment. You should call an ambulance or go to hospital immediately if you have diabetes and:

  • you’re being sick
  • you feel very thirsty
  • you need to pee more than usual
  • you have tummy pain
  • your breath smells fruity (like pear drop sweets or nail varnish)
  • you’ve fainted
  • you’re breathing more quickly or deeply than normal
  • you feel very tired or sleepy
  • you feel confused

If you can’t call an ambulance because you feel too unwell, ask someone nearby to do so.

What are the symptoms of type 1 diabetes?

When you first develop type 1 diabetes, you may have various symptoms, including:

  • feeling very thirsty
  • peeing often, particularly at night
  • feeling very tired
  • losing weight and muscle, without meaning to
  • feeling generally unwell

These symptoms can develop quickly, over weeks or even days. Other symptoms include:

If you don’t receive treatment for diabetes, your blood glucose level can become very high (


Hyperglycaemia (high blood glucose)

The symptoms of high blood glucose are similar to the main symptoms of diabetes, but they can come on suddenly and feel severe. They include:

  • extreme thirst
  • a dry mouth
  • blurred vision
  • drowsiness
  • needing to pee often

If left untreated, high blood glucose levels can lead to

diabetic ketoacidosis
, which is a serious condition where the body breaks down fat and muscle for energy, instead of glucose. This leads to a build-up of acids in your blood, which can cause
, loss of consciousness and even death.

Causes of type 1 diabetes

Type 1 diabetes is an autoimmune condition in which your immune system (the body's natural defence against infection and illness) mistakes the cells in your pancreas as harmful and attacks them. The pancreas usually produces the hormone insulin, which moves glucose out of your blood and into your cells, where it’s turned to energy. But because the pancreas is damaged in type 1 diabetes, people with the condition stop making the insulin that’s needed to move glucose out of your bloodstream.

It’s not known why some people develop type 1 diabetes, but research suggests a viral infection may play a role.

Type 1 diabetes is usually inherited (runs in families), so the condition may also be caused by the genes you have.

If you have a close relative, such as a parent, brother or sister, with type 1 diabetes, you have about a 6% (6 in 100) chance of also developing the condition. The risk for people who don't have a close relative with type 1 diabetes is less than 1 in 100.

Diagnosing type 1 diabetes

If you have the symptoms of diabetes, or think you do, see your doctor as soon as possible. They will ask you about your symptoms and may do urine and blood tests.

Urine test

Urine doesn’t usually contain glucose, but if you have diabetes, some glucose can overflow from the kidneys and into the urine. If your doctor suspects you may have type 1 diabetes, they may test your urine for glucose. They may also test your urine for chemicals known as ketones, which the body can make when you have type 1 diabetes.

Blood tests

There are 3 types of blood tests that can be used to help diagnose type 1 diabetes:

  • fasting blood glucose – a test to measure your blood glucose levels after an 8- to 10-hour fast (usually in the morning, before you’ve had anything to eat)
  • random blood glucose – a test to measure your blood glucose levels at any time of the day
  • oral glucose tolerance test (OGTT) – a test to measure your blood glucose levels after drinking a glucose drink.

Treating type 1 diabetes

Diabetes can’t be cured, but

can help keep your blood glucose levels as normal as possible, which is important for preventing future health problems.

If you’re diagnosed with diabetes, you may be referred to a diabetes care team for specialist treatment. Your care team or doctor can explain your condition to you in detail and help you understand your treatment. They will also closely monitor your condition.

As your body can’t produce any insulin, you will need to have regular insulin treatment to keep your glucose levels normal. You'll need to learn how to match the insulin you inject to the food you eat, taking into account your blood glucose level and how much exercise you do. This is a skill that needs to be practised and learnt gradually. Speak to your doctor or care team for advice on finding support services or courses that teach how to manage your insulin needs.

Insulin comes in several different forms, each of which works slightly differently.

Insulin injections

If you have type 1 diabetes, you’re likely to be treated with insulin injections. Insulin must be injected because if it was taken as a tablet, it would be broken down in your stomach, just like food, and wouldn’t be able to enter your bloodstream.

When you’re first diagnosed, your diabetes care team will usually show you:

  • how to inject insulin yourself
  • when to inject it
  • how to store your insulin
  • how to safely dispose of your needles

Insulin injections are either given with a syringe or an injection pen. Different people need different amounts of insulin each day. Your doctor or diabetes care team will let you know how many injections you'll need daily. They may also teach 1 of your close friends or relatives how to inject the insulin properly.

Insulin pump therapy

In some cases, your doctor may recommend insulin pump therapy instead of insulin injections. An insulin pump is a small device that holds and pumps insulin into the layer of tissue just under your skin. The pump is attached to you by a long, thin piece of tubing, with a needle at the end, which is inserted under your skin. Most people insert the needle into their stomach, but you can also insert it into your hips, thighs, buttocks or arms.

The pump allows insulin to flow into your bloodstream at a rate you can control, which means you may not need to give yourself regular injections. But you'll still need to monitor your blood glucose levels to make sure you’re receiving the right amount of insulin.

Different types of insulin act differently. Some work very quickly, but don’t last very long (rapid-acting insulin). Others take longer to act, but can last up to a whole day (long-acting or background insulin). There are also other types of insulin that lie in the middle. These are known as short- and intermediate-acting insulin. Whether you have an insulin pump or injections, your treatment may include a combination of these different types of insulin.

Monitoring your blood glucose levels

Many things can affect your blood sugar levels, so an important part of managing diabetes is making sure your blood glucose level remains as normal and stable as possible.

Most people can do this by using insulin treatment and eating a balanced, healthy diet. But you'll also need to regularly check your blood glucose levels to make sure they aren’t too high or too low.

In most cases, you'll be able to check your blood glucose levels at home using a simple finger prick blood test. Your doctor or diabetes care team will usually tell you when and how often to check your blood glucose level.

In general, useful times to measure your blood glucose level include:

  • at different times in the day
  • before a meal
  • 2 to 3 hours after a meal
  • during and after vigorous sport or exercise
  • before going to bed
  • if you think you have low blood glucose (hypoglycaemia)

If you have another illness (e.g. a cold or infection).

Having your blood glucose levels checked

As well as monitoring your blood glucose levels every day, your doctor or diabetes care team will usually also carry out a special blood test, known as a HbA1c test. This shows how stable your glucose levels have been over the past 6 to 12 weeks, and how well your treatment plan is working. Exactly how often you'll need this test will depend on various factors, such as how well your blood glucose levels are controlled and how long ago you were diagnosed with diabetes.

A high HbA1c level may suggest that your blood glucose level is high most of the time, which means your diabetes treatment plan may need to be changed.

Treating hypoglycaemia (low blood glucose)

Hypoglycaemia can happen when your blood glucose level becomes very low, usually below 4mmol/L.

It’s usually caused by:

  • not eating enough carbohydrates in your last meal
  • waiting too long to eat
  • taking too much insulin
  • doing lots of exercise without eating enough carbohydrates or reducing your insulin dose
  • drinking alcohol on an empty stomach

Mild hypoglycaemia (also known as a 'hypo') can come on quickly, causing symptoms, such as:

  • sweating
  • feeling shaky and trembling
  • being anxious or irritable
  • feeling hungry
  • difficulty concentrating
  • blurred sight

If you notice these symptoms, you should eat or drink something sugary to quickly raise your blood glucose level. Try:

  • 1 glass or a small can of a non-diet sugary drink
  • 1 glass of fruit juice
  • 3 dextrose or glucose sweets
  • 5 small sugary sweets

But take care not to eat fatty, sugary foods, like chocolate or cake, because they don’t raise your blood glucose as well as fat-free sugary foods. You should avoid eating or drinking too much sugar, if you do, your glucose levels may go too high.

Check your blood glucose after 10 minutes, and eat something sugary again if it’s still low.

Symptoms of severe hypoglycaemia include:

  • drowsiness
  • confusion
  • fainting

If this happens, you'll need to inject glucagon into your muscle. Glucagon is a hormone that quickly increases your blood glucose levels.

Your diabetes care team may show several of your family members and close friends how to inject the glucagon or glucose, should you need it.

After the glucagon injection, you should eat something sugary when you’re alert enough to safely do so. If you lose consciousness during a hypoglycaemic attack (hypo), there’s a chance it could happen again within a few hours, so you should rest afterwards and have someone stay with you.

If injecting glucagon into your muscle doesn’t work and you still feel drowsy or are unconscious 10 minutes after the injection, you, or whoever is with you, should call an ambulance immediately.

If you have type 1 diabetes, you should carry identification, like a medical alert bracelet or card, with you to help people better understand what’s happening if you become hypoglycaemic.

Islet transplantation

Some people with type 1 diabetes may benefit from a procedure known as islet transplantation. It involves implanting healthy islet cells from the pancreas of a deceased donor into the pancreas of someone with type 1 diabetes.

Islet transplants have been shown to help reduce the risk of severe ‘hypos’.

Other treatments

Type 1 diabetes can lead to long-term complications. If you have it, your risk of developing

heart disease
kidney disease
rises. To reduce the chance of developing these conditions, your doctor may recommend you take:

Complications of type 1 diabetes

Diabetes can cause many different health problems if it’s poorly treated or not treated at all. This is because having large amounts of glucose in the blood can damage blood vessels, nerves and organs.

Complications of type 1 diabetes include:

  • heart disease and stroke
  • pain and loss of feeling (nerve damage)
  • kidney problems
  • foot and circulation problems
  • sight problems and blindness

Heart disease and stroke

Having poorly-controlled blood glucose levels for a long period of time can increase your risk of developing

This can reduce blood flow to your heart, causing
(a dull, heavy or tight pain in the chest). It also increases the chance that a blood vessel in your heart or brain will become completely blocked, leading to a
heart attack

Nerve damage

High blood glucose levels can damage your nerves, causing a tingling or burning pain that spreads from your fingers and toes up through your arms and legs. If the nerves in your digestive system are affected, you may develop symptoms, like nausea, vomiting,


Kidney disease

If the small blood vessels of your kidney become blocked and leaky, your kidneys won’t work as well as they should.

In some cases, this can lead to

kidney failure

Foot problems

If the nerves of your feet become damaged, you may develop small nicks and cuts without noticing them. This can lead to a

foot ulcer,
which can cause serious infection.

Sexual dysfunction

In men with diabetes, particularly those who smoke, nerve and blood vessel damage can lead to

erection problems.
This can usually be treated with medication.

Women with diabetes may also notice sex-related changes, including:

  • a reduced sex drive or pleasure from sex
  • vaginal dryness
  • a reduced ability to
  • pain during sex

Speak with your doctor if you notice or are worried about the complications that diabetes can sometimes cause.

Living with type 1 diabetes

If you have type 1 diabetes, you'll need to

look after your health
carefully. Doing so will also make treating your diabetes easier and help reduce your risk of complications.

Lifestyle changes you can make include:

  • eating a
    healthy, balanced diet
    and exercising regularly — doing so can help lower your blood glucose level
  • stopping smoking (if you smoke) — this can help reduce your risk of developing a
    cardiovascular disease
  • looking after your feet — keep your nails short, wash your feet daily, wear shoes that fit properly, see a foot specialist regularly, check your feet for cuts and blisters regularly, and see your doctor if you have a minor foot injury that doesn't start to heal within a few days
  • have your eyes tested at least once a year to check for


If you have diabetes and are thinking about having a baby, speak to your doctor or diabetes care team, as managing diabetes can be harder during pregnancy.

It's also important to keep your blood glucose levels well-controlled before and during pregnancy to reduce the risk of complications.

Where to find more support for living with diabetes

Many people find it helpful to talk to others in a similar position.

Speak to your doctor or diabetes care team for advice on local support groups for people with diabetes.

Key points:

  • diabetes is a lifelong condition that causes a person's blood glucose (sugar) level to become too high. There are 2 main types: type 1 and type 2
  • you should call an ambulance or go to hospital immediately if you have diabetes and you’re being sick, feel very thirsty, you have tummy pain, you’ve fainted or you’re breathing more quickly or deeply than normal. Type 1 diabetes is usually inherited (meaning it runs in families)
  • if you’re diagnosed with diabetes, you may be referred to a diabetes care team for specialist insulin treatment. For example, you may need to have insulin injections
  • diabetes can cause complications if it’s poorly treated or not treated at all, such as kidney problems. This is because having large amounts of glucose in the blood can damage blood vessels, nerves and organs

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.