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Type 1 diabetes

Type 1 diabetes is a lifelong condition in which your body can't control levels of glucose in the blood. It develops when your body can’t produce insulin.

About 2.9 million people in the UK have been diagnosed with diabetes. There are two main types of diabetes: type 1 and type 2. Type 1 diabetes is the rarer form, affecting 15 out of every 100 people (including children) with diabetes. You may also hear type 1 diabetes called insulin-dependent diabetes and sometimes juvenile-onset diabetes.

Type 1 diabetes can develop at any age, but usually begins during childhood or adolescence.

Type 1 diabetes develops when your body can’t produce insulin. Insulin is a hormone (a chemical produced naturally by your body) that regulates the level of glucose in your blood. Glucose is a simple form of sugar found in foods and sugary drinks. It's absorbed by your body as a natural part of digestion and is carried around your body in your blood. When glucose reaches your body tissues, for example your muscle cells, insulin helps it enter the tissue where it's converted into energy.

Insulin is produced by your pancreas, which is a gland located behind your stomach. A shortage of insulin causes glucose to build up in your blood. This means your blood sugar levels become too high.


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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
    • have unexplained weight loss
    • be extremely tired
    • have blurred vision

    The symptoms can develop quickly, usually over a few weeks. If you have any of these symptoms, see your GP.

  • Diagnosis Diagnosis of type 1 diabetes

    Your GP will ask about your symptoms and examine you. You’re likely to have a number of tests, including:

    • a urine test – this will be checked for glucose and ketones
    • 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 beforehand

    If your urine tests positively for ketones and you have a raised blood glucose level, this suggests a diagnosis of type 1 diabetes.

    If you're diagnosed with type 1 diabetes, you will usually be referred to a clinic that has nurses and doctors who specialise in treating diabetes.

  • Treatment Treatment of type 1 diabetes

    There isn't a cure for type 1 diabetes but you can control it with medicines and lifestyle changes. You will need to monitor your blood glucose level carefully.


    Type 1 diabetes is controlled by taking insulin. This helps glucose to be absorbed into your cells where it’s converted into energy, which stops it building up in your blood.

    There are two main ways of taking insulin.

    Insulin injections

    These are the most common form of treatment, where you inject insulin under your skin. You will usually inject yourself before meals, using either a small needle or a pen-type syringe with replaceable cartridges.

    Portable insulin pumps

    These may be appropriate if you find it difficult to control your blood glucose with regular injections, despite careful monitoring. Insulin pumps can be programmed to inject you with insulin at a rate that you can control.

    There are several different kinds of insulin that work at different rates and act for different lengths of time. Ask your doctor or diabetes specialist nurse for advice on which type and method is best for you. For more information, see our frequently asked questions.


    By making the following lifestyle changes you can help control your blood glucose levels.

    • Eat a healthy, balanced diet with regular meals, three times a day. Include carbohydrates, such as pasta or potatoes, in each meal. If you have hypoglycaemia from time to time, it's a good idea to keep some sugary food or glucose tablets with you.
    • 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 control your blood glucose levels.
    • Only drink alcohol in moderation 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. This is because you already have an increased risk of developing circulatory problems and cardiovascular disease. Smoking further increases your risk of developing these diseases.

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

  • Worried about diabetes?

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  • Monitoring your blood glucose level Monitoring your blood glucose level

    You can use a home test kit to monitor your blood glucose level. This involves regularly taking a pinprick of blood from the side of your fingertip and putting a drop on a testing strip. A meter will read the result automatically.

    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

    Your GP or diabetes specialist nurse will show you how to monitor your blood glucose level. He or she will also tell you how often you need to check it.

    You may also need to have your levels of glycosylated haemoglobin (HbA1C) tested at least once a year. HbA1C is a protein that is produced when you have high blood glucose levels over a long period of time. The HbA1C test is done by taking blood from a vein in your arm or sometimes a drop of blood from a fingerprick. It’s used to see how well you’re controlling your blood sugar levels.

  • Causes Causes of type 1 diabetes

    Type 1 diabetes develops when the cells in your pancreas that make insulin (beta cells) are destroyed by your body's immune system. The reasons why your body’s immune system does this aren’t fully understood at present, but it's possible that environmental or genetic factors may trigger the attack.

  • Complications Complications of type 1 diabetes

    If type 1 diabetes isn't diagnosed or controlled properly, you can develop blood glucose levels that are either too high (hyperglycaemia) or too low (hypoglycaemia).


    Your blood glucose levels can become too high if you’re stressed or unwell, your insulin dose is too low, you miss doses or you eat too much carbohydrate. Hyperglycaemia can cause you to be more thirsty than usual, feel tired and have headaches.

    In some people who have diabetes, glucose can build up in the blood and reach dangerous levels. This is called diabetic ketoacidosis. It can cause you to vomit, breathe faster than usual and give your breath a distinctive 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 sugar is raised for a number of years, it can increase your risk of:

    • kidney failure
    • nerve damage
    • blindness
    • heart disease
    • stroke
    • foot ulcers – leading to foot or lower leg amputation


    Your blood glucose levels 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 do more physical activity than usual. Hypoglycaemia (also known as a ‘hypo’) can cause you to feel faint, sweaty, confused and you may feel your heart pounding. Treat it straight away by eating glucose tablets (or a few sweets or a sugary drink), followed by a couple of biscuits or a sandwich.

    If you don't treat hypoglycaemia, you may have fits and become unconscious, and if it’s very severe, hypoglycaemia can be fatal. For more information, see our frequently asked questions.

  • Glycaemic index Glycaemic index


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  • FAQs FAQs

    Can I drive if I have type 1 diabetes?


    If your diabetes is under control, you should be able to drive a car. However, you may not be able to drive a heavy goods vehicle or passenger vehicle (such as a minibus). You will need to contact the Driver and Vehicle Licensing Agency (DVLA) to inform them about your condition. You also need to tell your motor insurer about your condition.


    In the interest of road safety, you must be sure that you can safely be in control of a vehicle at all times. If you have type 1 diabetes, there is a chance that your blood glucose levels could become too low (hypoglycaemia or a ‘hypo’) when you’re driving. This could endanger you and other drivers.

    When you apply for a driving licence you will need to let the DVLA know that you have type 1 diabetes. The DVLA will contact your doctor for more information about how your condition is managed and whether you have any complications that might mean it’s unsafe for you to drive.

    You will usually be given a licence that lasts at most three years. Your condition will be assessed each time you reapply.

    You will 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
    • 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
    • don't drive for more than two hours without stopping for a snack
    • keep some kind of carbohydrate, such as sweets and a sugary drink, in your car

    If you develop hypoglycaemia 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 all your symptoms have gone – this usually takes about 45 minutes

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

    Can I go on holiday if I have type 1 diabetes?


    Yes, it's fine to go abroad on holiday if you have diabetes so long as you’re well prepared.


    People with diabetes travel all over the world and take the same kinds of holiday as people without the condition. However, it makes sense to plan well. Bear the following in mind when you go on holiday.

    • You, and the people you travel with, should know how you behave if you develop hypoglycaemia and know how to treat it.
    • Consider carrying or wearing some form of medical identification bracelet, tag or similar stating you have diabetes, particularly if you're travelling alone.
    • If you're travelling across time zones, you may need to adjust your insulin. Get advice from your doctor or diabetes specialist nurse.
    • If you become unwell while you're away, drink plenty of fluids and if you can't eat, make sure you have sugary drinks. If you can't eat or drink anything, go to hospital for treatment.
    • Security regulations at airports may mean you have to make special arrangements to travel with insulin. Carry diabetes identification and a letter from your doctor, and check with the airline you're flying with before you go.
    • Declare your condition when you buy travel insurance and never travel without it.

    If you have any questions or concerns about travelling, speak to your doctor or diabetes specialist nurse.

    How important is it to manage low blood glucose level?


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


    Part of the treatment for type 1 diabetes is making sure that your blood glucose levels are as near to normal as possible. Your 'normal' 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

    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.

    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 be caused if you miss a meal, don’t eat enough foods containing carbohydrate or take part in physical activity without eating enough to compensate for it. 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). Therefore, it’s important to monitor your blood glucose levels regularly – ideally two to four times daily. Most people get warning signs before hypoglycaemia, such as:

    • sweating
    • going pale
    • feeling your heart pounding
    • being confused
    • feeling sick
    • feeling irritable
    • being shaky

    If you develop hypoglycaemia, you must 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 whether it's returning to normal. Your blood glucose levels should start improving within 15 minutes of you eating or drinking something. If they don’t and you still have symptoms of hypoglycaemia, call for emergency help immediately.

    How will type 1 diabetes affect my work?


    Although being diagnosed with type 1 diabetes can leave you feeling worried about work, it shouldn't stop you from having an enjoyable and fulfilling career.


    Type 1 diabetes can potentially have an impact on many areas of your life, including work. How you manage your condition and control your diabetes can influence how well you cope with work and the choices you make. Your doctor or diabetes specialist nurse can give you more information and advice about your individual circumstances.

    If you have type 1 diabetes, you may have to make some adjustments to fit in with your life at work. For example, make sure you’re as fit and well as possible. This means having well controlled blood glucose levels and taking your insulin as planned. You may need to make changes to your meals if you work shifts, or if food isn't readily available. You will need to plan ahead to make sure you keep your blood glucose levels stable.

    It’s important to remember that you’re protected at work by the Disability Discrimination Act. Your employer has to make ‘reasonable adjustments’ to allow you to do your job, for example by giving you time off for appointments, or making sure you have enough breaks to eat regularly.

    There are, however, some careers that you won’t be able to pursue if you have type 1 diabetes – for example you can't join the armed forces. Also, you won’t be allowed to drive a police or health emergency vehicle. There are also restrictions in place for jobs that involve driving a heavy goods vehicle or a passenger carrying vehicle (for example a minibus). Otherwise, there are very few jobs that you won’t able to do.

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


    It’s very important that you’re particularly careful to control your blood glucose level before and during your entire pregnancy. If you don’t manage your diabetes well during pregnancy, you and your baby are at an increased risk of serious complications.


    To ensure you have a healthy pregnancy, you will need to have excellent blood glucose control before you get pregnant and maintain this during your entire 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
    • recurrent skin, vaginal and urinary tract infections
    • miscarriage or stillbirth

    There are also risks for your baby. He or she may not develop properly and is at risk of jaundice (yellowing of the skin) and breathing problems. Not controlling your diabetes well may also mean your baby is much bigger than usual at birth. A big baby increases both you and your baby’s risk of being injured during 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 very important that you speak to your doctor or diabetes specialist nurse. You will need to plan carefully to ensure that your pregnancy is healthy and successful. You will be monitored regularly, both 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 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 pregnancy.
    • You may need to change your regular 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.
    • It’s important that you continue to eat a healthy, balanced diet but you may need to make some changes to ensure you’re getting all the vitamins and minerals you need. You may need to adjust your diet throughout your pregnancy.
    • Keep a daily record of your glucose levels and monitor your glucose levels four to seven times a day 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 pregnancy. You may need more insulin in early pregnancy and then less from eight to 16 weeks (especially if you have loss of appetite or morning sickness). As your pregnancy progresses, your insulin needs will increase.

    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?


    There are three groups of insulin – human, analogue and animal. Within these groups there are different types of insulin that work at different speeds and for different lengths of time in your body.


    Human insulin is actually a synthetic (artificial) version of the insulin that is naturally made 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. Most people use human or analogue insulin, but some still use animal insulin because it works best for them.

    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 are 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 and can last up to six hours.
    • 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 need. You will learn to adjust your insulin dose yourself day-to-day so that your blood glucose levels stay stable.

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

  • Resources Resources

    Further information


    • Type 1 diabetes. BMJ Best Practice., published 21 June 2012
    • Diabetes – type 1. NICE Clinical Knowledge Summaries., published December 2010
    • Type 1 diabetes. Diabetes UK., published January 2009
    • Diabetes in the UK 2012 (April 2012): key statistics on diabetes. Diabetes UK., published April 2012
    • Diabetes – factsheet 312. World Health Organization. published September 2012
    • Diabetes mellitus. The Merck Manuals., published December 2012
    • Diabetic ketoacidosis (DKA). The Merck Manuals., published December 2012
    • Management of diabetes. Clinical guideline 116. Scottish Intercollegiate Guidelines Network (SIGN), March 2010.
    • Diagnosis and management of type 1 diabetes in children, young people and adults. National Institute for Health and Care Excellence (NICE), July 2004.
    • What is DAFNE? DAFNE., published March 2012
    • Insulin therapy in type 1 diabetes. NICE Clinical Knowledge Summaries., published December 2010
    • Large for gestational age. The Merck Manuals., published February 2009
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