Type 1 diabetes

Expert reviewer, Dr Jonathan Katz, Consultant Endocrinologist
Next review due June 2021

Type 1 diabetes is a lifelong condition in which your body can't control the amount of glucose (sugar) in your blood. If you have type 1 diabetes, your body can’t make insulin so your blood glucose becomes too high.

Doctor talking to a patient

About type 1 diabetes

There are two main types of diabetes: type 1 and type 2. Type 1 diabetes can develop at any age, but usually starts in children (between five and 15), or adults under 50. About 3.5 million people in the UK are diagnosed with diabetes, and up to one in 10 of those have type 1.

Insulin is a hormone (a chemical made by your body) that controls the amount of glucose in your blood. It helps glucose move from your blood into your body tissues – like your muscle cells – when you need a quick form of energy. If you have type 1 diabetes, your body can’t produce insulin so glucose can’t move into your cells and your blood glucose level becomes too high.

There isn’t a cure for type 1 diabetes. But if you take measures to control your blood glucose properly, you should be able to live a normal life with diabetes. It shouldn’t stop you from doing any of the activities you’d normally do.

Symptoms of type 1 diabetes

If you have type 1 diabetes, you may:

  • go to the toilet (to wee) more than usual
  • feel constantly thirsty
  • lose weight
  • feel extremely tired and weak
  • have blurred vision
  • be prone to infections

If you have any of these symptoms, see your GP straightaway.

An image showing the liver and surrounding structures

Diagnosis of type 1 diabetes

Your GP will ask about your symptoms and examine you. They may ask you to have some tests to see whether or not you have diabetes. These may include the following.

  • A urine test to check your levels of glucose and ketones. Your body makes ketones when it burns fat. This happens when you can’t use glucose for fuel.
  • A fingerprick test. This is also known as a random glucose test and involves taking a sample of your blood to test how much glucose it contains. If you have a level of glucose in your blood that’s more than 11mmol/litre, you’re likely to have diabetes.
  • A random glucose test. This involves taking a sample of your blood to test how much glucose it contains. If you have a level of glucose in your blood that's more than 11mmol/litre, you're likely to have diabetes.

You might have some more tests at hospital. These might include a blood test to measure a type of antibodies in your blood that can be found in people with type 1 diabetes.

Treatment of type 1 diabetes

There isn't a cure for type 1 diabetes. But you should be able to control your diabetes by taking insulin and making some simple changes to your lifestyle. You’ll also need to check your blood glucose level regularly to make sure you’re taking the right dose of insulin.

If you're diagnosed with type 1 diabetes, your GP will refer you to a hospital clinic that specialises in treating diabetes. The doctors and nurses there will give you advice and support so you can manage your diabetes at home.


Taking insulin is an essential part of managing type 1 diabetes. It helps to control your blood glucose level and keep it as close to normal as possible. Your GP or hospital clinic will start you on insulin as soon as you’re diagnosed with type 1 diabetes. You’ll need to take it for the rest of your life, sometimes several times a day. It may take a while for your body to adjust when you start taking insulin for the first time.

There are different types of insulin, and different ways you can take it. The types of insulin are classified by how quickly they work and how long they last for (for example, rapid-acting, short-acting and long-acting). You can take insulin by injections or through insulin pumps. Your doctor or diabetes specialist nurse will discuss with you what type of insulin and method of taking it will work best for you. This may depend on your age, eyesight, ability to inject yourself or use pumps, and how well your blood glucose is controlled.

For more information about insulin, see our FAQ below: What are the different kinds of insulin?

Insulin injections

Injecting insulin is the most common form of treatment. You usually inject insulin into your upper arm, thighs, buttocks or tummy (abdomen) before you have meals. It’s best to change the exact spot that you use within the injection site each time. This is because insulin can cause fat to grow more quickly around the injection site, causing soft lumps to build up under your skin.

You may be given either a small needle to use, or a pen-type syringe with replaceable cartridges. If you have problems with your eyesight or using your hands, have a chat with your doctor to see what’s the best option for you.

Portable insulin pumps

These are devices that are attached to your body and deliver insulin through a small tube called a cannula that lies just under your skin. They deliver a regular, or constant amount of insulin into your body. You may find these easier if you need to have several injections a day, or if you find it difficult to control your blood glucose with regular injections. Insulin pumps may also be recommended for children under 12 who are having the same problems. For children under 12, pump therapy is considered an option if taking multiple injections every day isn’t practical for some reason.

Monitoring your blood glucose level

You can keep an eye on how well you’re controlling your diabetes by checking your blood glucose level regularly. It’s best to test your blood at least four times a day. You might need to do this before meals, after meals and when you go to bed, and before you exercise, for example. You’ll be given a blood glucose meter, so you can do this at home.

To test your blood glucose, you’ll need to take a pinprick of blood from the side of your fingertip and put a drop on a testing strip. Wash and dry your hands in warm water beforehand so your blood flows more freely. You place the testing strip into a glucose meter, which reads it and shows you the result automatically. Your GP or diabetes specialist nurse will talk you through how to do this, and tell you how often you need to check your glucose level.

For some people, an alternative to testing your blood is continuous glucose monitoring. This involves putting a small device just under your skin, which measures your blood glucose levels every few minutes. This information is transmitted to a display device. You can see your levels over time and it will alert you if it gets too high or low. There are a few different types of continuous glucose monitoring devices available. Ask your doctor for more information about them.

Your 'normal' blood glucose range will be specific to you, but a general guide for adults is:

  • when you wake up and before you have breakfast: 5 to 7mmol/litre
  • before you have meals at other times of the day: 4 to 7mmol/litre

Monitoring your blood glucose level this way will help you understand how to adjust your insulin dose according to how much carbohydrate you eat. Ask your clinic if they run structured education classes such as DAFNE (Dose Adjustment For Normal Eating). These courses can help you learn how to adjust your insulin dose.

Your GP will also monitor how well you’re controlling your glucose level by asking you to have regular blood tests for glycosylated haemoglobin (HbA1C). HbA1C is a measure of how much glucose has been taken up by your red blood cells. It shows how high your blood glucose level has been, or how well you’ve been controlling it over the previous two to three months.

Causes of type 1 diabetes

Type 1 diabetes is caused by the cells in your pancreas that make insulin being destroyed – usually by your body's immune system. This is called an autoimmune reaction. It’s not yet clear exactly what triggers your body’s immune system to attack these cells.

You’re more likely to develop type 1 diabetes if the condition runs in your family, so the reaction may be genetic. But it seems that other things might trigger the autoimmune reaction. Other theories for triggers include a virus, chemicals in your environment, certain foods or physical or emotional stress. Sometimes, people can have diabetes without doctors finding any reason why, and this is called idiopathic type 1 diabetes.

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Complications of type 1 diabetes

Your blood glucose level may become either too high, which is called hyperglycaemia, or too low (hypoglycaemia).


You might develop hyperglycaemia before your type 1 diabetes is diagnosed and controlled properly. Your blood glucose level can also become too high if you’re unwell, if your insulin dose is too low or if you eat a lot of carbohydrate. Mild hyperglycaemia doesn’t usually cause any symptoms. But you may find that you’re thirstier than usual, wee more often and feel tired as your blood glucose level continues to rise.

If your blood glucose continues to rise, it can reach dangerous levels. This is called diabetic ketoacidosis. It can give you stomach ache and make you be sick. Your heart might feel like it’s pounding and you’ll likely breathe faster than usual too. Your breath may have a distinctive fruity smell too. Diabetic ketoacidosis is a medical emergency and can potentially be fatal if you aren’t treated in hospital immediately.

Over the longer term, if your blood glucose isn’t controlled properly and stays too high, it can lead to a number of problems. These include:

  • kidney failure
  • nerve damage, which can cause tingling or burning sensations, or cause numbness and make you lose your sense of touch or temperature altogether
  • foot ulcers – eventually if serious, your foot or lower leg may need to be amputated
  • damage to your vision, which could even make you blind
  • heart disease
  • stroke
  • peripheral arterial disease
  • persistent or regular infections, especially urinary and skin infections


Hypoglycaemia (also known as a ‘hypo’) is when your blood glucose level becomes low – this is a possible complication of treatment (taking insulin).

Hypoglycaemia can happen if you take too much insulin, skip or delay a meal, or are unwell. It can also drop too low if you’re more active than usual. Alcohol and physical activity can cause delayed hypoglycaemia (sometimes up to 24 hours later). So, it’s important to monitor your blood glucose level regularly.

Your GP or diabetes specialist nurse will tell you how often you should be checking your blood glucose level. Most people get warning signs before hypoglycaemia. You might:

  • feel hungry
  • sweat a lot
  • feel your heart pounding
  • feel irritable
  • feel shaky and nervous
  • get tingling lips
  • feel dizzy or confused
  • have blurred vision

If you develop hypoglycaemia, take glucose tablets or gels, or drink a glass of milk or juice straightaway. After 10 to 15 minutes, test your blood glucose level to see if it's returning to normal. If it hasn’t, have something more to drink or take more glucose tablets and re-test your blood glucose levels after another 15 minutes. Once your blood glucose levels start to get back to normal, eat something that contains longer-lasting carbohydrates such as a sandwich, or a meal with potatoes or pasta.

If your blood glucose level doesn’t return to normal and you still have symptoms of hypoglycaemia, call for emergency help immediately.

If you don't take steps to deal with hypoglycaemia, it can eventually cause you to have a fit and you’ll lose consciousness. If it’s very severe, hypoglycaemia can be fatal; so it’s essential that you can recognise the signs and know how to treat them. Your healthcare team may give you a prepared injection of a medicine called glucagon to take if you have a hypo and lose consciousness. They’ll show a family member or friend how to use it.

It’s a good idea to wear a medical emergency identification bracelet or similar, so that people know you have diabetes and take insulin.

If you’re having hypos quite a lot, your doctor or specialist diabetes nurse may recommend you get some extra help. They may refer you to a Blood Glucose Awareness Training (BGAT) programme.

Living with type 1 diabetes

It’s important to follow a healthy lifestyle if you have diabetes. This may help to control your glucose level, and reduce your risk of developing complications.

  • Eat a healthy, balanced diet with regular meals. Include carbohydrates, such as pasta or potatoes, in each meal. Low glycaemic index (GI) foods give a more gradual climb in your blood sugar after meals and may help improve blood sugar control. See our topic on Carbohydrates for more information about this. Examples of low GI foods include whole grain varieties of bread, breakfast cereals such as porridge, and sweet potatoes. But don’t feel you have to restrict yourself to just low GI foods. A dietitian can help you to plan the best diet to manage your diabetes.
  • Aim to exercise regularly to get the benefits of exercise. For tips and advice on how to do this, see our topic: Exercise - getting started. This will help you to stay a healthy weight and reduce your risk of high blood pressure and high blood cholesterol.
  • If you drink alcohol, stick within recommended sensible limits.
  • If you smoke, try to stop. Smoking is unhealthy for everyone, but it's especially bad if you have diabetes. Diabetes increases your risk of developing circulatory problems, heart disease and stroke. Your risk is even higher if you smoke and have diabetes too.

It’s important to have regular eye examinations, dental check-ups, foot checks, cholesterol tests and blood pressure checks. This will help to diagnose any complications early on so that they can be treated. It’s also a good idea to have an annual flu vaccination and a pneumococcal vaccination.

Being diagnosed with a long-term medical condition, such as diabetes, can be difficult to come to terms with. It’s important to discuss your feelings with your specialist diabetes nurse or GP as they can talk through any concerns you have. It may also help to talk to other people with diabetes to get tips and advice on how they manage their condition. Support groups like Diabetes UK (see Other helpful websites below for contact details) are a good start and can put you in touch with a local group.

Frequently asked questions

  • If your diabetes is under control, you should be able to drive a car or motorbike as normal.

    If you have type 1 diabetes, there’s a chance that your blood glucose level could become too low and you could have a hypo (hypoglycaemia) when you’re driving. As soon as you’re diagnosed with type 1 diabetes, you need to contact the Driver and Vehicle Licensing Agency (DVLA).

    You’ll need to sign a form and agree to comply with the directions of your doctor treating your diabetes. And if there are any changes to your condition, such as worsening retinopathy (a complication that can distort your vision) or you lose awareness of hypoglycaemia, you’ll need to report these to the DVLA immediately. You’ll usually be given a licence that lasts up to three years. Your diabetes and its management will be assessed each time you reapply. You also need to let your motor insurer know about your diabetes and your use of insulin.

    You need to be able to recognise the signs of hypoglycaemia and know how to treat it if it happens when you're driving. Here are some tips.

    • Check your blood glucose level before you start a journey, even if it’s a short one.<
    • Have a snack before you drive if your blood glucose level is 5mmol/litre or less.
    • Don’t drive for more than two hours without checking your blood glucose level again.
    • Keep some form of fast-acting carbohydrate, such as sweets and a sugary drink, in your car.

    If you feel you’re having a hypo when you're driving:

    • pull over and stop somewhere safe
    • take glucose tablets immediately
    • don't start driving again until 45 minutes after your blood glucose level is back to normal

    The rules are stricter to drive a heavy goods vehicle or passenger vehicle (such as a minibus) – contact the DVLA for more information.

  • Most women with diabetes have normal healthy babies. But it’s really important to have excellent blood glucose control before and during your pregnancy.

    If you don’t manage your diabetes well during pregnancy, it may put you at an increased risk of serious complications, such as:

    • high blood pressure (pre-eclampsia)
    • having your baby early (preterm labour)
    • miscarriage or stillbirth

    You also need to keep your glucose level as close to normal as possible for the health of your baby so they can develop properly. If you don’t control your diabetes, they could be at risk of jaundice and breathing problems after you give birth. And they might be bigger than usual at birth, so you might need to have a caesarean.

    Your doctor or diabetes specialist nurse will give you advice and information about things you can do to ensure you have a healthy pregnancy. These may include the following.

    • Have a general health check to make sure you don’t have any underlying problems with your kidneys, eyes or heart, which could increase your risk of complications.
    • Start taking 5mg of folic acid daily from the time you stop contraception until week 12 of your pregnancy.
    • Be aware that you may need to change your usual insulin or any other medicines that you take (such as statins or ACE inhibitors). This is because certain medicines are harmful to a developing baby.
    • Monitor your glucose level at least four times a day and keep a record of the results, to help you achieve excellent control.

    You’ll need to have extra tests and regular monitoring during your pregnancy – ask your diabetic specialist nurse for information about this.

  • There are three groups of insulin – human, analogue and animal. In each of these groups, there are different types of insulin that work at different speeds and for different lengths of time.

    Human insulin is actually a synthetic (artificial) version of the insulin that’s made naturally in your body. Analogue insulin is a synthetic variation of human insulin. All synthetic insulin is designed to work in the same way as natural insulin.

    There are six main types of insulin.

    • Short-acting insulins. You should inject these about 30 minutes before meals, and they can last up to nine hours.
    • Rapid-acting analogues. You inject this type five to 15 minutes before you eat. It usually starts working within 15 minutes and lasts two to five hours.
    • Intermediate- and long-acting insulins. You need to inject this type once or twice a day. They’re most active between four and 12 hours and can last up to 36 hours.
    • Long-acting analogues. These need to be injected once or twice a day and can last up to 24 hours.
    • Mixed insulin. This is a mix of intermediate- and short-acting insulin.
    • Mixed analogue. This is a mix of intermediate-acting insulin and rapid-acting analogue.

    When you're first diagnosed with type 1 diabetes, your doctor or diabetes specialist nurse will recommend what type of insulin you should try. They’ll help you to understand how to adjust your insulin dose yourself every day, so that your blood glucose level stays stable.

    Ask at your clinic whether they run education classes such as DAFNE (Dose Adjustment For Normal Eating). This is an intensive course that helps you learn how to adjust your insulin dose.

  • If you’re struggling with managing your type 1 diabetes, it can be really beneficial to get some help and advice. Your doctor should be able to direct you to open-access services on a walk-in and telephone-request basis during working hours. They can also give you contact information for a helpline staffed by people with specific diabetes expertise on a 24-hour basis. Your doctor will keep you up to date with information about diabetes support groups (both local and national), too, and how to contact them.

    You might find it really helps to talk to other patients about how they manage their condition, as they may have some useful practical tips. There are diabetes charities that might be able to put you in touch with people or let you know if there is a local support group where you live. See Other helpful websites for contact details.

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  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, June 2018
    Expert reviewer, Dr Jonathan Katz, Consultant Endocrinologist
    Next review due June 2021