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Type 1 diabetes

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.

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 or adults under 40. About 3.3 million people in the UK are diagnosed as having diabetes, and about one in 10 of those have type 1 diabetes.

If you have type 1 diabetes, your body can’t produce insulin. 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, you don’t have enough 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 taking measures to control your blood glucose properly means that 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.

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  • Symptoms Symptoms of type 1 diabetes

    If you have type 1 diabetes, you may:

    • pass more urine than usual
    • be constantly thirsty
    • lose weight
    • be extremely tired
    • have blurred vision
    • be prone to infections 
    These symptoms can develop quickly, usually over a few weeks. If you develop these symptoms, see your GP.
  • Diagnosis Diagnosis of type 1 diabetes

    Your GP will ask about your symptoms and examine you. They may ask you to have a number of tests to determine 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 don’t have enough insulin so 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.
    • A fasting blood glucose test. You will need to have this test at a time when you haven’t eaten anything for at least eight hours.
  • Treatment 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 simple changes to your lifestyle. You will 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, you’ll be referred 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 are diagnosed with type 1 diabetes. You’ll need to take it for the rest of your life, sometimes two or more 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 methods for taking 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 use injections or pumps and how well your blood glucose is controlled.

    Insulin injections

    Insulin injections into your skin are the most common form of treatment. You usually inject insulin before meals into your upper arm, thighs, buttocks or abdomen. You may be given either a small needle to use, or a pen-type syringe with replaceable cartridges. Insulin pens are more discreet than the injections. You may find them easier to use if you have problems with your eyesight or using your hands.

    Portable insulin pumps

    These are portable devices that are attached to your body by a catheter. They deliver a 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 need several injections every day.

    See our section below on different types of insulin for more information.

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  • Monitoring your blood glucose level 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. 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. You place the testing strip into the 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 also tell you how often you need to check your glucose level.

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

    • before meals: 4 to 7mmol/litre
    • two hours after meals: less than 9mmol/litre

    Monitoring your blood glucose level will help you understand how to adjust your insulin dose according to how much carbohydrate you eat. Ask at your clinic whether 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 Causes of type 1 diabetes

    Type 1 diabetes occurs when the cells in your pancreas that make insulin are destroyed by your body's immune system. This is called an autoimmune reaction. It’s not yet clear 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 can trigger the autoimmune reaction, such as a virus, chemicals in your environment, certain foods or stress.

  • Complications Complications of type 1 diabetes

    If you can’t control your blood glucose level properly, your blood glucose may become either too high (hyperglycaemia) or too low (hypoglycaemia).


    Before your type 1 diabetes is diagnosed and controlled properly, you may develop hyperglycaemia. Your blood glucose level can also become too high if you’re unwell, if your insulin dose is too low or if you eat too much carbohydrate. Mild hyperglycaemia doesn’t usually cause any symptoms. But you may find that you are thirstier than usual, pass urine 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 cause you to be sick and breathe faster than usual. Your breath may have a distinctive fruity acetone smell, similar to pear drops or nail varnish. Diabetic ketoacidosis is a medical emergency and can be fatal if you aren’t treated in hospital immediately.

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

    • kidney failure
    • nerve damage, which can cause tingling or burning sensations, or make you lose your sense of touch or temperature altogether
    • damage to your vision, which could lead to blindness
    • heart disease
    • stroke
    • foot ulcers – which can eventually lead to foot or lower leg amputation
    • persistent or regular infections, especially urinary and skin infections


    Your blood glucose level can become too low if you don't eat enough foods that contain glucose. It can also drop too low if you take too much insulin or are more active than usual. Hypoglycaemia (also known as a ‘hypo’) can make you feel faint, sweaty and confused, and you may feel your heart pounding. If you start to feel like this, taking some glucose tablets (or eating a few sweets or a sugary drink), can quickly make you feel better.

    If you don't take steps to deal with hypoglycaemia, it can eventually cause you to have a fit and become unconscious. If it’s very severe, hypoglycaemia can be fatal. For more information, see our frequently asked questions.

    You may wish to wear a medical emergency identification bracelet or similar, so that people know you have diabetes and take insulin.

  • Living with type 1 diabetes Living with type 1 diabetes

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

    • Eat a healthy, balanced diet with regular meals, three times a day. Include carbohydrates, such as pasta or potatoes, in each meal. A dietitian can help you to plan the best diet to manage your diabetes.
    • Aim to do 150 minutes of moderate exercise over a week in bouts of 10 minutes or more. 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, don’t drink to excess and stick within the recommended daily limits.
    • If you smoke, stop. Smoking is unhealthy for everyone, but it's especially important to stop if you have diabetes. Having diabetes increases your risk of developing circulatory problems, heart disease and stroke. Your risk is even higher if you smoke and have diabetes too.

    You should 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 recommended that you have an annual flu vaccination and a pneumococcal vaccination if you have diabetes.

    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. Visit the Diabetes UK website to find your local diabetes support group.

  • Glycaemic index Glycaemic index


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  • Can I drive if I have type 1 diabetes? Can I drive if I have type 1 diabetes?


    If your diabetes is under control, you should be able to drive a car or motorbike as normal. But you may not be able to drive a heavy goods vehicle or passenger vehicle (such as a minibus).

    More information

    If you have type 1 diabetes, there’s a chance that your blood glucose level could become too low (hypoglycaemia or having a ‘hypo’) when you’re driving. This could put your life and the lives of others at risk. So it’s important to make sure that you can drive safely. As soon as you’re diagnosed with type 1 diabetes, you need to contact the Driver and Vehicle Licensing Agency (DVLA). This applies to anyone who takes insulin for their diabetes. If you don’t yet have a driving licence, you need to tell the DVLA about your diabetes as soon as you apply for one.

    The guidelines vary for different types of vehicles (for example, cars or heavy goods vehicles).The DVLA assesses each case separately. This usually involves contacting your doctor for more information about how you manage your condition and whether you have any complications. 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 tell your motor insurer about your diabetes and your use of insulin. Some insurance companies cater specifically for people with chronic conditions such as diabetes.

    You need to be able to recognise the signs of hypoglycaemia and know how to treat it if it happens when you're driving. To help prevent hypoglycaemia:

    • check your blood glucose level before you start a journey, even if it’s a short one
    • don’t drive for more than two hours without checking your blood glucose level
    • carry your glucose meter and testing strips with you in the car
    • eat a snack before driving if your blood glucose level is 5mmol/litre or less
    • don't drive with a blood glucose level of less than 4mmol/litre • keep some form of carbohydrate, such as sweets and a sugary drink, in your car

    If you start to feel unwell when you're driving:

    • pull over and stop somewhere safe
    • take glucose tablets or some other form of fast-acting carbohydrate immediately
    • leave the driver's seat and take the keys out of the ignition to make it clear that you're no longer in charge of the car
    • don't start driving again until your blood glucose level is back to normal – this usually takes about 45 minutes

    If you need further information, speak to your doctor, diabetes specialist nurse or the DVLA.

  • How important is it to manage low blood glucose level? How important is it to manage low blood glucose level?


    It's important to keep your blood glucose level as stable as possible if you have type 1 diabetes. If you don’t monitor your condition regularly and your blood glucose level gets low, you may become very unwell.

    More information

    Managing type 1 diabetes involves making sure that your blood glucose level is as near to normal as possible. Everyone’s 'normal' blood glucose range is specific to them. But a general guide for adults is:

    • before meals: 4 to 7mmol/litre
    • two hours after meals: less than 9mmol/litre

    If your blood glucose level drops below 4mmol/litre, this is known as hypoglycaemia or a 'hypo'. If hypoglycaemia isn't treated, you may become unconscious and, if it’s severe, it can be fatal. It’s essential that you can recognise the signs of hypoglycaemia and know how to treat them.

    Hypoglycaemia can happen if you take too much insulin. Anyone who takes insulin as a treatment for their diabetes could develop hypoglycaemia. It can also happen if you’re unwell, miss or delay a meal or exercise vigorously or for a long time. Another cause can be drinking too much alcohol or drinking alcohol without eating beforehand.

    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, such as:

    • feeling hungry
    • sweating
    • going pale
    • feeling your heart pounding
    • being confused
    • feeling irritable
    • being shaky
    • tingling lips
    • blurred vision

    If you develop hypoglycaemia, eat or drink something sugary straight away. Then eat something containing longer-lasting carbohydrates such as a sandwich, toast or a piece of fruit. Test your blood glucose level to see if it's returning to normal. Your blood glucose level should start going back to normal within 15 minutes of you eating or drinking something. If it doesn’t and you still have symptoms of hypoglycaemia, call for emergency help immediately.

  • How can I ensure I have a healthy pregnancy? I have type 1 diabetes and want to have a baby. How can I ensure that I have a healthy pregnancy?


    It’s important that you control your blood glucose level carefully before and during your pregnancy. If your diabetes isn’t well controlled during pregnancy, you and your baby are at an increased risk of complications.

    More information

    Most women with diabetes have normal healthy babies. But to make sure you have a healthy pregnancy, you need to have excellent blood glucose control before and during your pregnancy. Not managing your diabetes carefully during pregnancy may put you at an increased risk of serious complications, such as:

    • high blood pressure (pre-eclampsia) – this can affect both you and your baby and lead to serious health problems
    • skin, vaginal and urinary tract infections that keep coming back
    • miscarriage or stillbirth

    Your baby’s health is also at risk if you don’t keep your glucose level as close to normal as possible. Your baby may not develop properly during the pregnancy, and they may be at risk of jaundice (yellowing of the skin) and breathing problems after the birth. Not controlling your diabetes well may also mean your baby is much bigger than usual at birth. A big baby makes it more likely that you or your baby are injured during the birth. It’s also more likely that you will need to give birth by caesarean.

    If you have diabetes and are planning to have a baby or are pregnant, it’s important to speak to your doctor or diabetes specialist nurse. You will need to plan carefully to make sure that your pregnancy is healthy and successful. You’ll be monitored regularly, before and during your pregnancy, by doctors and nurses who are experienced in managing diabetes in pregnancy.

    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.

    • If necessary, lose excess weight before you get pregnant, as being overweight increases your risk of complications.
    • 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.
    • 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.
    • Continue to eat a healthy, balanced diet during your pregnancy. You may need to adjust your diet to make sure you’re getting all the vitamins and minerals you need.
    • Monitor your glucose level four to seven times a day and keep a record of the results, to help you achieve excellent control.

    During your pregnancy, you will need to have extra tests and regular monitoring. This is because your insulin needs will change throughout your pregnancy.

    For more information about the changes you need to make during pregnancy, speak to your doctor or diabetes specialist nurse.

  • What are the different kinds of insulin? What are the different kinds of insulin?


    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.

    More information

    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. These should be injected about 15 to 30 minutes before meals and can last up to eight hours.
    • Intermediate- and long-acting insulins. These are injected once or twice a day. They’re most active between four and 12 hours and can last up to 30 hours.
    • Rapid-acting analogues. These are injected shortly before, with or after meals. They usually start working straight away.
    • Long-acting analogues. These need to be injected once 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.

  • Other helpful websites Other helpful websites


    • Diabetes mellitus. PatientPlus., reviewed 2 July 2013 
    • Management of type 1 diabetes. PatientPlus., reviewed 11 October 2012
    • What is diabetes? Diabetes UK., accessed 16 June 2015
    • What is type 1 diabetes? Diabetes UK., accessed 16 June 2015
    • Insulin. Reference range. Medscape., reviewed 14 February 2014
    • Pediatric type 1 diabetes mellitus. Medscape., reviewed 30 September 2014
    • Diabetes-type 1. Clinical Knowledge Summaries., reviewed December 2014 
    • Type 1 diabetes. BMJ Best Practice., reviewed 12 August 2014
    • Ketones. Medscape., reviewed 9 January 2013
    • Type 1 diabetes mellitus treatment and management: Medscape., reviewed 21 April 2015
    • Diabetes. Oxford handbook of endocrinology and diabetes (online). 3rd ed. Oxford Medicine Online., published March 2014
    • Therapy-related issues: endocrine system. Oxford handbook of clinical pharmacy (online). 2nd ed. Oxford Medicine Online., published January 2012
    • Insulin regimes. PatientPlus., reviewed 13 January 2014 
    • Nursing patients with endocrine problems. Oxford handbook of adult nursing (online). Oxford Medicine Online., published August 2010
    • Joint Formulary Committee. British National Formulary (online). London: BMJ Group and Pharmaceutical Press., accessed 16 June 2015
    • Diabetes diet and exercise. PatientPlus., reviewed 20 April 2011 
    • Diabetes. Oxford handbook of nutrition and dietetics (online). 2nd ed. Oxford Medicine Online., published January 2012
    • Management of diabetes. Scottish Intercollegiate Guidelines Network (SIGN), March 2010.
    • Self-monitoring in diabetes mellitus. PatientPlus., reviewed 21 July 2014 
    • Diabetes mellitus (DM). The Merck Manuals., reviewed June 2014 Type 1 diabetes mellitus. Medscape., reviewed 21 April 2015
    • Diabetic ketoacidosis. Medscape., reviewed 29 October 2014 
    • Oxford handbook of general practice (online). 4th ed. Oxford Medicine Online., published April 2014 
    • Endocrinology. Oxford handbook of clinical medicine (online). 9th ed. Oxford Medicine Online., published January 2014 
    • Emergency management of hypoglycaemia. PatientPlus., reviewed 6 February 2015 
    • Diabetes in pregnancy: management of diabetes and its complications from preconception and the postnatal period. Introduction. National Institute for Health and Care Excellence (NICE) Guidelines NG3, February 2015.
    • Diabetes in pregnancy. PatientPlus., reviewed 17 March 2015 
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