Diabetes treatment and the safe use of insulin

If you take insulin to manage your diabetes, it is important to use it safely. This avoids the level of sugar (glucose) in your blood becoming too low or too high.

Insulin treatment improves many people’s quality of life and saves other people’s lives. It is used to lower your blood sugar level if you have diabetes. But errors with insulin treatment are common and can cause harm.

Errors can happen if you do not:

For your safety, you also need to store insulin and dispose of used needles in the correct way.

The main side effect of insulin treatment is low blood sugar. This is called hypoglycaemia or a hypo. You need to know the symptoms of low blood sugar, and how to treat and avoid hypos.

Using the right type of insulin

There are more than 20 different types of insulin. Your healthcare professional talks to you about which type or types of insulin might best suit your needs.

The packaging of insulin is often similar and so are insulin names. For example, these insulin names are sometimes confused with each other:

  • Humalog with Humalog Mix 25 or Humalog Mix 50
  • Humulin S with Humulin I or Humulin M3
  • Humalog with Humulin I, Humulin S or Humulin M3
  • NovoRapid with NovoMix 30
  • Levemir with Lantus
  • Hypurin Porcine Neutral with Hypurin Porcine 30/70 Mix

It is important to order your insulin at least 2 days in advance. Your pharmacist might not always have your insulin in stock.

Check with your pharmacist that the name of your insulin and the insulin device or cartridge are correct before you leave the pharmacy. It is a good idea to keep a record of these details.

Having the right dose of insulin

Insulin comes in:

  • glass bottles (vials) for insulin syringes and pumps
  • cartridges for insulin pens
  • pre-filled pens

Each device should be clearly labelled with the name of the insulin. You need to keep a record of how many units of insulin you take.

There are 2 different designs of insulin cartridge. This means that not every cartridge is suitable for all insulin pens. If you use cartridges, you need to know which pen is suitable and safe for your treatment.

Insulin is prescribed in units. If someone writes the letter "U" after the dose instead of the full word "units", this can cause confusion. The "U" can be mistaken for an "0". There is a chance that you could have too much insulin (an overdose), such as 40 units instead of 4.

If someone else gives you your insulin, always check the amount (dose) with them.

Injecting insulin in the right way

If you inject insulin, it is important to do this in the right way and have a good injection technique. Diabetes UK has guidance about this and a video on how to inject insulin in 7 simple steps.


  • inject insulin at a 90 degree angle
  • use your upper outer thighs, buttocks and tummy (abdomen) as injection sites
  • gently lift the skin to make sure that you inject insulin into fat
  • inject into a different patch of skin each time. This avoids you getting fatty lumps under your skin (lipohypertrophy). If you inject insulin into these fatty lumps, there will be a delay before your body can take it in (absorb it)
  • change your insulin pen needle every time that you inject

Taking insulin at the right time

People take insulin at different times. You might have insulin when you wake up, before eating or at bedtime.

Please ask a healthcare professional to explain when you need to take your insulin.

If you have to stay in hospital and are well enough, you can ask to keep your insulin with you. This means that you can continue to manage your own diabetes while you are in hospital.

If you cannot take or keep your own insulin, the nurses can give it to you instead. Do not be afraid to ask them when you need your insulin.

Storing insulin and disposing of used needles

You need to store unopened supplies of insulin in the fridge. Insulin must not freeze.

When you have started to use insulin, you can keep it at room temperature for up to 1 month. Avoid storing the insulin in direct sunlight or heat, such as on window sills or near radiators. For more information about storing insulin, you can read the leaflet in the insulin box. 

Make sure that you have enough supplies of insulin, especially when you go on holiday.

It is important that you always dispose of used needles in a sharps bin. This is a specially designed box with a lid that you can get on prescription. Depending on where you live, your local council might collect your sharps bin for disposal when it is full.

Resource number: 3477/VER3
Last reviewed: October 2022
Next review due: October 2025

A list of sources is available on request.

Trusted Information Creator. Patient Information Forum

Contact us

If you have any questions or concerns about your diabetes medicines, please speak to the staff caring for you. 

You can also contact our pharmacy medicines helpline.

Phone: 020 7188 8748, Monday to Friday, 9am to 5pm

Email: [email protected]

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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