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Type 1 diabetes


Expert reviewer, Paul McArdle, Registered Dietitian
Next review due January 2024

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 a hormone called insulin. This means that your blood glucose level 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 usually starts in children, between the ages of five and 15. But you can develop it as an adult too. Fewer than one in 10 people diagnosed with diabetes have type 1.

If you have type 1 diabetes, your body can’t produce a hormone called insulin. This hormone usually controls the amount of glucose in your blood. Insulin helps glucose move from your blood into your body tissues – for example, your muscle cells – when you need energy. Without it, glucose can’t move into your cells and your blood glucose level becomes too high.

Type 1 diabetes is caused when the cells in your pancreas that make insulin are destroyed – usually by your body's immune system. This is called an autoimmune reaction. There seem to be genetic factors involved in developing type 1 diabetes – you’re more likely to develop it if the condition runs in your family. But other factors in the environment may also act as a trigger in people who are susceptible to the disease.

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Symptoms of type 1 diabetes

If you have type 1 diabetes, you may:

  • need to pee more than usual
  • feel constantly thirsty
  • lose weight
  • feel extremely tired and weak
  • have blurred vision

The symptoms of type 1 diabetes tend to develop quite quickly. If you notice these symptoms in yourself or your child, contact your GP as soon as possible.


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Diagnosis of type 1 diabetes

Your GP will ask about your symptoms and examine you. To diagnose diabetes, you’ll need to have a blood test to measure your glucose level. Your GP may also ask you to have a urine test.

If your blood glucose level is high (above 11 mmol/litre), it’s likely that you have diabetes. Your GP will refer you to a specialist diabetes team, who will be able to confirm the diagnosis and start treatment straight away. You might have some more tests at the hospital. These might include blood tests for particular antibodies and proteins that can be markers for type 1 diabetes.

Management of type 1 diabetes

There isn’t a cure for type 1 diabetes. But having insulin treatment, alongside other measures to control your blood glucose, means you should be able to live a normal life. Type 1 diabetes shouldn’t stop you from doing any of the activities you’d normally do.

You’ll usually have a team of diabetes specialists managing your care. They’ll devise a care plan or package of care which will be regularly reviewed. The team will be able to talk you through everything you need to know about living with diabetes and how to manage your condition.

Insulin

Taking insulin is an essential part of managing type 1 diabetes. This is because insulin helps to control your blood glucose level and keep it as close to normal as possible. Your doctor will start you on insulin as soon as possible after you’re diagnosed with type 1 diabetes. You’ll need to take it for the rest of your life.

There are different types of insulin. Nowadays, most people take insulin that’s made in a laboratory, and mimics the natural insulin in your body. Insulin medication is classified by how quickly it works and how long it lasts – for example, rapid-acting, short-acting and long-acting. This makes a difference to how frequently you need to take it. You might take your insulin in the following ways.

  • Injections. This is the most common form of treatment. You usually inject insulin into your thighs, buttocks or tummy (abdomen) using a pen-type device. You might need to have the injections before every meal and/or throughout the day.
  • Insulin pumps. These are devices that deliver a regular or constant amount of insulin through a small tube called a cannula that lies just under your skin. Your doctor may recommend this method if your blood glucose isn’t controlled with regular injections or if you’re finding multiple injections difficult.

Your doctor or diabetes specialist nurse will discuss with you what type of insulin and method of taking it will work best for you.

Diet

There are no restrictions on what you can or can’t eat if you have type 1 diabetes – but you should aim to follow a healthy, balanced diet. It’s a good idea to include some healthy carbohydrates such as wholegrains and fruit and vegetables with each meal. This will help to control your blood glucose level.

You’ll need to plan your insulin treatment quite closely around what you eat. Your dietitian might talk to you about ‘carb counting’, which means matching the amount of insulin you take to the amount of carbohydrate you’re eating. This may help you to be more flexible with your mealtimes and what you eat, depending on what insulin you’re taking.

Monitoring your blood glucose level

A key part of managing your diabetes is checking your blood glucose level regularly – usually several times a day. You’ll usually do this with a device that takes a pinprick of blood from the side of your fingertip. Sometimes, your doctor will recommend other ways to monitor your blood glucose level. These include flash and continuous glucose monitors, which you wear just underneath your skin, and which continuously record your glucose level.

Monitoring your blood glucose level will help you to understand how to adjust your insulin dose according to your diet, physical activity and illness. You should be offered structured education classes such as the DAFNE (dose adjustment for normal eating) programme to help you with this.

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.

Complications of type 1 diabetes

You may develop complications with diabetes if your blood glucose level becomes either too high (hyperglycaemia), or too low (hypoglycaemia).

Hyperglycaemia

Treatment aims to keep your blood glucose at a normal level. But if you’re unwell or stressed, miss an insulin dose or eat more carbohydrate than your body can deal with, it may become too high (hyperglycaemia). You may find that you’re thirstier than usual, need to pee more often and feel tired.

If you don’t have enough insulin, chemicals called ketones build up in your blood. This might make you feel extremely tired or fatigued and feel sick or vomit. Some people notice their breath has a distinctive fruity smell. Your doctor will tell you how to check your ketone level, and what to do if it’s too high.

If the level of ketones continues to rise, it can become dangerous. This condition is called diabetic ketoacidosis (DKA) and is a medical emergency – you may develop severe dehydration and go into shock. You should seek medical help immediately if you develop these symptoms.

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

  • kidney disease
  • nerve damage, which can cause tingling, burning sensations or loss of feeling
  • foot ulcers
  • damage to your eyes, which can lead to loss of vision
  • heart disease and stroke
  • persistent or regular infections, especially urinary and skin infections

Hypoglycaemia

Hypoglycaemia (also known as a ‘hypo’) is a possible complication of treatment with insulin. It happens when your blood glucose level becomes too low (usually below 4mmol/litre). Hypoglycaemia can happen if you take too much insulin, skip or delay a meal or misjudge the amount of carbohydrate you need. It can also happen if you’re more active than usual or if you drink alcohol.

Most people get warning signs when their glucose level begins to fall. These include:

  • feeling hungry
  • sweating a lot
  • feeling your heart pounding
  • being anxious or irritable
  • feeling shaky
  • tingling lips

If your blood glucose level continues to fall, you may start to feel dizzy or confused, weak and lethargic and develop blurred vision. Hypoglycaemia can be dangerous if not dealt with quickly.

If you notice symptoms of hypoglycaemia, you need to eat or drink 15 to 20g of a fast-acting carbohydrate straight away. Examples include glucose tablets or gels, and sugary drinks such as juice or a full-sugar fizzy drink. Check your blood glucose level after 10 to 15 minutes and if it hasn’t returned to normal, have something more to drink or take more glucose tablets. Once your blood glucose level starts to get back to normal, you may need to eat something containing longer-lasting carbohydrates such as bread, potatoes or pasta.

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 give it to you. If you don’t have glucagon or your blood glucose level doesn’t return to normal after taking it, call for emergency help immediately. It’s a good idea to wear a medical emergency identification bracelet or similar, so that people know you have diabetes and take insulin.

Living with type 1 diabetes

Following a healthy lifestyle can help to control your glucose level and reduce your risk of developing complications. Here are some key points.

  • Eat a healthy, balanced diet with regular meals, in combination with managing your insulin doses. What you eat is important for controlling your blood glucose level (see the information on diet in our section on management of type 1 diabetes). A healthy diet is also important for managing your weight and preventing cardiovascular disease. Aim to eat a diet low in fat, sugar and salt, and with at least five portions of fruit and vegetable every day.
  • If you smoke, try to stop. Smoking is unhealthy for everyone, but it's particularly 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.
  • Keep active. As well as helping to lower your blood glucose level, exercise can help you to stay a healthy weight and reduce your risk of cardiovascular disease.
  • If you drink alcohol, stick within the recommended limit of no more than 14 units a week, spread over several days. Make sure you don’t drink on an empty stomach because this can increase the risk of hypoglycaemia.

You’ll have regular reviews with your healthcare team, including screening for eye conditions, foot problems and kidney disease, as well as cholesterol tests and blood pressure checks. This will help to diagnose any complications early so that they can be treated.

Frequently asked questions

  • If your diabetes is under control, you should be able to drive a car or motorbike as normal. But you’ll need to contact the Driver and Vehicle Licensing Agency (DVLA) as soon as you’re diagnosed, as they’ll want to assess you and check that you’re safe to drive.

    There are strict rules for checking your blood glucose level before driving if you have diabetes. Always check your blood glucose before you drive and if it’s less than 5mmol/litre, don’t drive. Have a snack first and wait until your glucose level rises to at least 5mmol/litre. You also need to be able to recognise the signs of hypoglycaemia and know how to treat it if it happens when you're driving.

    The rules are stricter if you drive a heavy goods vehicle or passenger vehicle (such as a minibus) – visit the DVLA website for more information. If your condition changes, including problems with vision or loss of awareness due to hypoglycaemia, you must report these to the DVLA immediately.

  • Most women with type 1 diabetes have a healthy pregnancy. But there is a risk of complications. It’s important to plan for pregnancy and make sure your diabetes is under control before you start trying for a baby. It’s safest if your glycosylated haemoglobin (HbA1C) level is below 48mmol/mol before you get pregnant. Keeping your diabetes well controlled during your pregnancy will help to keep the risks as low as possible.

    If your diabetes isn’t well controlled, it may put you at an increased risk of serious complications such as high blood pressure (pre-eclampsia), miscarriage and stillbirth. There’s also a greater risk of your baby being born with complications such as spinal bifida. And you’re more likely to have a larger baby if you have diabetes, so you might need to have a caesarean.

    During pregnancy, you’re also at greater risk of diabetes complications such as eye and kidney problems. You’ll be offered extra tests and regular monitoring during your pregnancy to ensure your diabetes is under control and to reduce the risk of complications. Ask your diabetic specialist nurse or midwife for information about this. Your diabetes nurse can also help you to plan a healthy pregnancy.



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Related information

    • Type 1 diabetes. BMJ Best Practice. bestpractice.bmj.com, last reviewed 9 November 2020
    • Diabetes – type 1. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised November 2020
    • Insulin. Encyclopaedia Britannica. www.britannica.com, accessed 9 December 2020
    • Type 1 diabetes. Diabetes UK. www.diabetes.org.uk, accessed 9 December 2020
    • Type 1 diabetes in adults: diagnosis and management. National Institute for Health and Care Excellence (NICE), last updated 16 December 2020. www.nice.org.uk
    • Diabetes (type 1 and type 2) in children and young people: diagnosis and management. National Institute for Health and Care Excellence (NICE), last updated 8 November 2016. www.nice.org.uk
    • Insulin therapy in type 1 diabetes. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised July 2020
    • Insulin and diabetes. Diabetes UK. www.diabetes.org.uk, accessed 9 December 2020
    • I have type 1 diabetes – what can I eat? Diabetes UK. www.diabetes.org.uk, accessed 9 December 2020
    • Checking your blood sugar levels. Diabetes UK. www.diabetes.org.uk, accessed 9 December 2020
    • What is DAFNE? DAFNE. dafne.nhs.uk, accessed 10 December 2020
    • Hyperglycaemia (hypers). Diabetes UK. www.diabetes.org.uk, accessed 10 December 2020
    • Having a hypo. Diabetes UK. www.diabetes.org.uk, accessed 10 December 2020
    • Ketones and diabetes. Diabetes UK. www.diabetes.org.uk, accessed 8 January 2021
    • Personal communication, Paul McArdle, Registered Dietitian, 28 December 2020
    • Complications of diabetes. Diabetes UK. www.diabetes.org.uk, accessed 10 December 2020
    • What is a hypo? Diabetes UK. www.diabetes.org.uk, accessed 10 December 2020
    • A guide to insulin treated diabetes and driving. Driver & Vehicle Licensing Agency, revised September 2019. gov.uk
    • Planning for a pregnancy when you have diabetes. Diabetes UK. www.diabetes.org.uk, accessed 10 December 2020

  • Reviewed by Pippa Coulter, Freelance Health Editor, January 2021
    Expert reviewer, Paul McArdle, Registered Dietitian
    Next review due January 2024

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