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Insulin injections

Many people with type 1 in the UK inject their insulin through multiple daily injections. Learn more about injections, pens and needles.
Content last reviewed and updated: 07.12.2023

A man injecting insulin using a smart pen

How do I make insulin injections?

Insulin is injected into the fatty tissue below the skin. Your thighs, upper arms, buttocks and stomach are the best places to make insulin injections, but this should be discussed with your Diabetes Healthcare Team.

Rotating your injection site is important because if the fat beneath the skin gets hard or lumpy it can affect the way your body absorbs the insulin. In this case, it might not work the way it’s supposed to. Be careful not to inject into muscle either, because this can also affect the absorption of insulin and may cause hypoglycaemia as well as bruising.

Insulin pens

There are two main types of insulin pens; reusable pens, where you replace a cartridge in the pen when the insulin runs out, or pre-filled disposable pens, where you simply use a whole a new pen when your old one runs out.

Smart insulin pens are also available, which connect to an app to record how much insulin you’ve taken and when. Find out more about smart insulin pens.

What sort of needle should I use for insulin injections?

Using the right kind of needle is really important. Using the wrong needle can affect the way insulin gets into the body and lead to unpredictable highs and hypos, bruising around the injection site or even leaking insulin.

Needle length

Needles for insulin pens come in a variety of sizes up to 12mm long, but most people with type 1 use needles that are 4mm, 5mm or 6mm. Check the box you’ve been given to see what size your needles are.

In general, it’s best to use the shortest needle for the job, particularly when you first start injecting insulin. The Forum for Injection Technique recommends that:

  • Children and adolescents should use a 4mm pen needle regardless of age, gender or body mass index (BMI). There is no medical reason for recommending needles longer than 6 mm
  • 4mm pen needles are recommended for all adults regardless of age, gender or BMI. If people need to use needle lengths over 4mm or a syringe they must use a correctly-lifted skin fold to avoid intramuscular injections

However, if you are using a short needle and find a big drop of insulin on your skin after you pull it out, you may need a longer one. If your insulin tends to leak, it may help to deliver half your dose in one site, and then inject the other half at least 2 inches (5cm) away. Concentrated insulin (U-200 rather than U-100) might be another option to discuss with your Diabetes Healthcare Team.

Talk to your GP or Diabetes Healthcare Team about what length needle you should be using.

Needle tips

To make a pen needle for insulin injections, a thin tube of steel is sharpened to a point using three or five cuts. The one made with five cuts means the tip is thinner and it can go into the skin more easily, so you may find this easier to use.

You can talk to your GP about needle tips. If your needles have been changed, talk to your GP if you would prefer to keep using the ones you’re used to. They might need input from your Diabetes Healthcare Team or consultant, who you can ask to write to your GP.

Product quality

Insulin pen needles are medical devices. It’s important that they work well and meet international standards – and they usually do. However, if you find a problem with your needle, it’s important to report problems so they can be addressed.

If you have a needle that’s not safe or that doesn’t work properly:

  • Save it in a puncture-proof container so you can send it back to the manufacturer if they ask you to
  • Call the manufacturer’s customer care line to report it – these details should be printed on the box
  • If you have been through a whole box of needles and some were bad, report it using the MHRA Yellow Card scheme. Tell them what was wrong and how many of the needles were faulty

If you regularly have problems with your pen needles and you want to switch to a different brand, talk with your GP or Diabetes Healthcare Team.

Can you recycle insulin pens?

Novo Nordisk’s PenCycle scheme is a great way to recycle any pre-filled insulin pens. Find more information on the Pencyle website.

More about insulin

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A woman preparing to inject insulin


There are different types of insulin and methods of delivering insulin to the body.

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A smart insulin pen and mobile app

Smart insulin pens

A smart insulin pen is a reusable self-injection pen, which records information about how much insulin you inject and the timing of it.

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An insulin pump

Insulin pumps

Insulin pumps can improve glucose control in people with type 1 diabetes but do not suit everyone.

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A woman holding and reading a insulin pump

Can I get an insulin pump on the NHS?

In England, Wales, Scotland and Northern Ireland you can get an insulin pump providing you meet certain criteria.