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Insulin and diabetes

What does insulin do?

Insulin is a hormone made in the pancreas, which is an organ in your body that helps with digestion. It helps your body use glucose (sugar) for energy. 

But when you have diabetes, sometimes your pancreas doesn’t make any insulin, doesn’t make enough or the insulin it makes doesn’t work properly (called insulin resistance). And that’s why some people with diabetes are insulin-dependent, which means they need to take it as medication. Taking insulin helps you manage your blood sugar levels. 

Everybody with type 1 and some people with type 2 diabetes need to use insulin as a treatment. You take it by injecting it using an insulin pen, or by using an insulin pump. Pumps aren’t available to everyone – only for people who have type 1 diabetes

If you need to inject insulin, we’ve made a video showing exactly how to inject in seven simple steps. And if you're nervous of injecting or don't like needles, that's completely natural, we've put together some tips to help you feel less worried about injections.

Your healthcare team will talk to you about insulin if they think it’s the right medication for you. Together you’ll agree the type you need and how much you need to take (your dose).

Insulin injections

Here’s Emma to show you how to inject insulin safely. There are seven simple steps and you can pause and rewind where you need to. If you know someone with diabetes or would like family and friends to understand more about injecting insulin, please click the share button and help others learn.


Your injection kit

To inject insulin safely you’ll need:

  • An insulin pen – this can be one that already has insulin in which you throw away after it’s empty, or a pen you can reuse by changing the insulin cartridge yourself.  
  • Your needle – this is small and thin, as it only has to go just under the skin, not into a muscle or vein. These can only be used once. 
  • A sharps bin or needle clipper – this is where you will safely throw away your needle. 

Everything you need is available for free on prescription

How to clean injection site, insulin pen and carry cases

To clean your skin before injecting insulin or to clean your insulin pen and carry case, use hot soapy water with a clean flannel or cloth. You don’t need separate wipes.

How to inject insulin 

  1. Wash and dry your hands.
  2. Choose where you’re going to inject – you’re looking for fatty tissue so the main injection sites are your stomach (in a semi-circle under your belly button), sides of your thighs and your bum. It’s vital you choose a different spot each time – at least 1cm or half an inch from where you last injected. If not, hard lumps can appear that will stop your body absorbing and using the insulin properly.
  3. Attach the needle to your pen – removing the outer and inner caps – and dial up two units of insulin. Point your pen upwards and press the plunger until insulin appears from the top of the needle. This is known as priming, and helps regulate your dose by removing any air from the needle and cartridge.
  4. Dial your dose and make sure the spot you’re injecting is clean and dry. To clean, use soap and warm water. You do not need to use alcohol wipes.
  5. Insert the needle at a right angle (90° angle). You might want to gently pinch the skin before injecting. Press the plunger until the dial goes back to 0.
  6. Count to 10 slowly to give the insulin time to enter your body before removing the needle.
  7. Throw away the needle using your needle clipper or sharps bin. Your healthcare team will tell you how to get rid of the bin safely when full.

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Insulin storage

You’re entitled to get your insulin for free on prescription, but make sure you’re clear on any forms you need to complete first. 

Your healthcare team will suggest how much to get and store at home, but most people get enough for three months. It’s a good idea to have two weeks' worth left when you put your repeat prescription in.

The best place to keep the insulin you're not using is in the fridge. This is because insulin needs to be kept at temperatures lower than 25°C (77°F). The ideal storage temperature is 2 to 6°C (36 to 43°F). For the insulin you're using on the day, room temperature is usually fine. But this can be higher if the heating is on or it’s summer, so keep an eye on this and put it in the fridge if you’re worried. 

But don’t put it in the freezer, as this may damage the insulin. And if you leave it out of the fridge for 28 days or more you’ll need to throw it away as the insulin will have broken down.

Some insulins may need to be stored slightly differently so make sure you read the information leaflet that comes with yours, or ask your healthcare team for more advice.

Top tips for insulin storage

  • Keep spare vials or cartridges of insulin in their boxes in the fridge.
  • Check the pack for the expiry date and don’t use it if it has expired.
  • Don’t expose insulin to sunlight or high temperatures, so no leaving it in the car on a hot day or near the cooker.
  • We have a loads of different cool bags in our online shop, to keep your insulin cool when you’re on the move or when you're on travelling abroad.

Insulin pump

An insulin pump is a battery-operated device that gives you insulin regularly throughout the day. It’s an alternative to injecting but it’s only available to people with Type 1 diabetes. We’ve got more information about insulin pumps if you need it.

Insulin pens

There are two types of insulin pens: 

  • a pen that already has insulin in which you throw away after it’s empty
  • a pen you can reuse with insulin cartridges that you change

Talk to your healthcare professional about which type of pen is right for you. 

There are also smart insulin pens available in the US. These automatically send information to an app on your phone, like the amount of insulin you have taken and at what time. which allows you to keep tabs of your diabetes management with a bit more ease. 

Smart pens aren’t currently available in the UK, but they could be soon. Keep an eye on our e-newsletter for all the latest diabetes tech. 

Insulin resistance

Insulin resistance is when the insulin that you produce, or the insulin you inject, doesn’t work properly. This can mean your blood sugar levels increase. Insulin resistance can happen if you have too much fat around your stomach, but it doesn’t only affect you if have obesity or overweight. 

Insulin resistance is more likely to happen as a teenager when hormones are unpredictable and can be completely unrelated to your weight. To reduce your insulin resistance you might need to start oral medications alongside your insulin, making insulin more effective again. Your healthcare team will advise you on the best method to reduce your insulin resistance.

Insulin and children 

If your child takes insulin, we’ve got all the information you and they need to start injecting themselves. Marley and Lauren will talk you both through it in our video. 

Insulin for type 2 diabetes

If you have type 2 diabetes and your doctor thinks insulin can help you, it doesn’t mean you now have type 1 diabetes. You still have type 2 diabetes, but you've changed treatment.

If you have type 2 diabetes, you may not need to use insulin straight away. But some people have very high blood sugar levels when they are first diagnosed. Insulin can be used as a short-term treatment to help quickly bring down your blood sugar levels. 

Some people may need to take insulin for a particular reason, like during pregnancy or a severe illness, or after surgery. But you may also need to start it as a treatment if other medications haven’t helped managed your blood sugar levels or are not appropriate for you. 

If you need insulin it isn’t your fault and it doesn’t mean you haven’t managed your diabetes well. It's simply another medication that can help to keep you as healthy as possible. Managing blood sugars effectively is really important in reducing your risk of future diabetes complications and insulin may be the most appropriate treatment choice for you. Many people with type 2 diabetes need to use it as treatment at some point. 

It’s still important to keep going to your appointments and manage your condition with healthy lifestyle choices. Staying active and eating a healthy diet will reduce the risk of complications from your diabetes. 

Types of insulin 

There are five different types of insulin and they all work slightly differently to manage your diabetes. Which ones you take will be decided between you and your healthcare team. 

Rapid-acting insulin 

You take rapid-acting insulin (sometimes known as fast-acting insulin) shortly before or after meals. It works very quickly, and it’s usually taken alongside an intermediate-acting insulin or long-acting insulin. Your dose will depend on how many carbohydrates you’re eating. You will see brands such as Novorapid, Flasp and Apidra if you take rapid-acting insulin. 

Short-acting insulin 

Short-acting insulin is similar to rapid-acting insulin, but is slightly slower. Because it’s slower, you need to take it around 25 minutes before you eat. It’s also called a bolus insulin, which means you take it around meal times. Actrapid and Humulin S are some brands you could be prescribed. 

Mixed insulin

This is a mixture of short-acting insulins and long-acting insulins. You still take it before meals, but you won’t have to take a background insulin as well. You may see brands such as Insuman Comb if you take mixed insulin. If you have type 2 diabetes, you might be prescribed this type of insulin. 

Cloudy insulins, such as premixed insulin, should be gently rolled and inverted (turned upside down) 10 times each until the crystals go back into suspension and the solution becomes milky white. You should not vigorously shake the insulin as this causes bubbles which could lead to inaccurate doses. Inversion and/or rolling should be performed a total of 20 times immediately before every injection with cloudy insulin.

Intermediate-acting insulin

Intermediate-acting insulin is also known as background insulin or basal insulin. This means it works throughout the day. It’s taken once or twice a day. Brands you may see include Humulin Isophane, Insulatard and Insuman Basal. 

Long-acting insulin 

Long-acting insulin is slower than intermediate insulin, but very similar in how your body processes it. You usually take it once a day, at the same time each day. Tresiba and Lantus are some brands you may be prescribed. It’s been shown to reduce the risk of hypos compared to intermediate-acting insulin – we’ve got more information on the possible side effects of taking insulin. Intermediate or long acting insulins are also more likely to be prescribed for people with type 2 diabetes. 

Insulin side effects  


Hypos are the most common side effect of taking insulin. Hypos are when your blood sugar is low, and they are very common when you take insulin. They can be caused by taking too much insulin. If you’re having a lot of hypos, you may be on the wrong dose and you should speak to your healthcare professional. We’ve got more information on the symptoms of hypos, as well as how to manage them.

General side effects

As with all prescribed medication, you may react differently to others when you take insulin. You should let your healthcare professional know if you have headaches, nausea or flu-like symptoms within the first 72 hours of starting any new insulin.

Avoiding injection bruises and lumps

Bruising can happen when you catch a tiny blood vessel under the skin where you have injected. It is quite normal for this to happen occasionally when you are injecting regularly and you’re not doing anything wrong. 

If you are concerned, you could make an appointment with your diabetes specialist nurse who will be able to do a review of your injection technique. In some cases, bleeding and bruising can be reduced by something as simple as using a different sized needle or changing your needle after each injection. 

Some people notice hard lumps that can form if you inject in the same place too often. This might be lipohypertrophy (also known as lipos), or could be something called cutaneous amyloidosis. These lumps can stop the insulin from working properly, so make sure you rotate where you inject and choose a different spot each time. If you notice any lumps, especially if they're not going away, speak to your healthcare professional for more advice.

Other side effects from injecting a lot can be itching, rashes and other skin irritations. Changing where you inject helps with this too. You can also get treatments from your local pharmacy that can will help with the irritation.

Weight gain

When you start taking insulin, you may start to put on weight. There are lots of reasons for this, like how much you take, your diet and the type of insulin you’re taking. If you’re worried about putting on weight, or you’d like some help losing weight, then we’re here to help

Insulin is a growth hormone, and any growth hormone you take can encourage weight gain.This is why your diet is so important, Insulin helps your body to use glucose from food as energy, and store any extra. But eating well and following a healthy lifestyle, can help you manage your weight.

When you’re diagnosed with diabetes you may have lost some weight in a short space of time, as this is one of the symptoms, and the weight regain may be an important part of the recovery if you've lost a lot of weight.

Similarly, if you’ve changed your diet to try and lose weight and are therefore using less insulin, switching back to your previous dose and eating patterns may mean you quickly put weight back on. So you may want to discuss new insulin doses with your healthcare team as you start to reintroduce more food.

How much insulin can affect your weight depends on the type of insulin you’re taking. Analogue insulin doesn’t cause much weight gain, but you’re more likely to put on weight if you take human insulin or animal insulin.

Dose is also very important. If you take too much insulin, this could lead to you putting on weight as well. Having low blood sugars, or hypos, makes you feel hungry too. If you are having frequent hypos you should talk to your healthcare team. 

Insulin overdose

Insulin overdose can happen if you take more insulin then you need. This can be very serious, and may lead to severe hypos. The worst cases can make you feel disorientated, cause you to have seizures and could even lead to death. 

If you think you’ve taken too much insulin accidentally, then eat a lot of fast-acting carbohydrate such as sweets or glucose tablets. 

If you’re worried about taking too much insulin, or think you may have taken too high a dose, contact your healthcare team, call NHS 111 or go to your local Accident and Emergency (A&E) department. 

You can also call our helpline for more advice and support. 

    Throwing away your needles and lancets 

    Sharps bins and needle clippers are the safest way of disposing of your insulin needles and your lancets. A needle clipper removes the needle from your insulin pen, and is useful when you’re out and about. How you get rid of your sharps bin depends on where you live. Your healthcare team should have information to help you get rid of your bin.

    What is insulin made of?

    Insulin is made in different ways. You and your healthcare team will discuss which insulin you can take. 

    • Human insulin – this is synthetic and made in a laboratory to be like insulin made in the body. 
    • Analogue insulin – the insulin molecule is like a string of beads. Scientists have managed to alter the position of some of these beads to create genetically engineered insulin known as analogues. 
    • Animal insulin – This isn’t used much anymore, but some people find that insulin from animals works best for them. It is usually from a cow or pig. 

    Insulin sensitivity and your dose 

    You may hear your healthcare professional talk about insulin sensitivity. This is how well your body is using insulin to get your blood sugar levels down. People with high sensitivity need less insulin than those with low sensitivity. 

    Your healthcare professional can test you for insulin sensitivity, and this will help them decide what dose of insulin you will need, and if insulin of you need it at all.

    Worrying about injections

    Many people worry or feel anxious about starting insulin injections. You might be scared of needles, feel squeamish about injecting, worried about pain, or some people even feel nervous or embarrassed about injecting in public. If you feel this way, you’re not alone. These feelings are natural but can be more serious if they start to impact on how you manage your diabetes, like skipping doses. 

    There are lots of things you can try that could help. Like finding out what makes you feel most comfortable with your injections. If you’re worried about the needle itself, talk to your healthcare professional. They can advise on the right needle length for you. And injecting really cold insulin is more uncomfortable, so check out our guide to storing your insulin so you know how to keep it cool but not too cold.

    Learning as much as you can about the benefits of insulin might also help you manage your feelings about the injections. Some people find that writing a list of questions and worries is a useful way of processing it all. Bring this list along to your next diabetes appointment and remember there are no silly questions or worries, they are all valid. Your healthcare professional will appreciate anything you mention and it will help them give you the best support.

    Try talking to others about it too – everyone’s different and you might learn some useful tips. Join one of our diabetes support groups or if you find it easier to chat to others online, use our online forum. You can also call our helpline to talk about your worries or ask us questions.

    We know that diabetes doesn't just affect you physically, it can affect you emotionally too. Whatever you're feeling, you are not alone. We’ve put together some emotional support information you might find helpful and that you might like to share it with your family and friends too.

    What happens if you avoid taking your insulin?

    If you have type 1 diabetes, taking insulin is essential and you cannot live without it. If you avoid taking it, your blood sugar (glucose) levels can become too high and you risk developing diabetic ketoacidosis (DKA). If left untreated, DKA could be life-threatening. That’s why it’s important to make sure you take your insulin. 

    If you have type 2 diabetes and use insulin to treat your condition, you should continue to take it as prescribed. If you avoid taking it, your blood sugar levels could become too high and you may become ill. Please speak to your healthcare professional if you have any questions or concerns about taking your insulin. 

    Insulin is a treatment that helps manage blood sugars, so this also reduces the risk of serious long-term complications as well a shorter-term consequences. It’s still important to keep going to your appointments and manage your condition with healthy lifestyle choices. Staying active and eating a healthy diet will reduce the risk of complications from your diabetes, but insulin is also an important part of your treatment. 

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