Some people with diabetes need to take insulin every day. Insulin is a hormone that helps the body manage blood sugar when a person injects it. The area of skin through which the injection occurs can change its effects.
A person cannot take insulin as a pill or oral medication. The enzymes in the stomach would break down the insulin before it reaches the bloodstream.
People use insulin injections to treat and manage diabetes alongside dietary and lifestyle changes, and oral medications.
For people who require insulin injections, different types of insulin are available. In this article, we explain how to follow the doctor’s instructions on how and where to inject insulin.
Image credit: Stephen Kelly, 2019
A person needs to inject insulin into the layer of fat directly under the skin, known as subcutaneous tissue, with a small needle or a device that looks like a pen.
Several different sites can support an insulin injection.
Abdomen
The abdomen is a common site for insulin injections that many people with diabetes choose. It is easy to access and often less painful than other sites due to protection by fat, greater surface area, and less muscle.
To give an injection into the abdomen, pinch a section of fatty abdominal tissue, with fingers either side.
The site should be between the waist and the hipbones about 2 inches away from the belly button.
Avoid injecting near any scar tissue on the abdomen.
Upper Arms
The upper arm is another possible site for insulin injection.
Place the needle into the tricep area at the back of the arm, about halfway between the elbow and the shoulder.
Difficult self-administration is the main disadvantage of this site. Getting enough of a pinch to administer the insulin can be tricky. A person might need assistance for an injection into the upper arm. They might also experience greater comfort while injecting into the non-dominant arm.
This means injecting into the left arm of a right-handed person or the right arm of a left-handed person.
Thighs
The thigh is a simple area for self-injection.
When choosing the thigh as an injection site, insert the needle into the front of the thigh, halfway between the knee and the hip. It should be slightly off center towards the outside of the leg.
The injection should take place around 4 inches, or about the width of a hand, above the knee and the same distance from the top of the leg. Avoid the inner thigh due to the denser network of blood vessels in that area.
Inject the medicine into a pinch of at least 1–2 inches of skin.
Though easy to access, regular injections in the thigh can sometimes cause discomfort when walking or running afterward.
Lower back, hips, or buttocks
The final site for administering an insulin injection is the lower back or hip.
To administer an injection here, draw an imaginary line across the top of the buttocks between the hips.
Place the needle above this line but below the waist, about halfway between the spine and the side.
As with the upper arm, this site is very difficult to use for self-injection and may require another person for administration. When injecting into the buttocks, avoid the lower part.
The body absorbs insulin at different speeds from each of the sites. This information can be useful when planning insulin injections:
- Abdomen: Insulin enters the bloodstream most quickly after an abdominal injection.
- Upper arms: The body absorbs insulin with moderate speed but slower than an injection in the abdomen.
- Lower back and thighs: Insulin enters the bloodstream most slowly from these sites.
- Administer rapid-acting insulin into the abdomen right after a meal for the fastest results.
Inject long-acting and intermediate-acting insulin into the other sites, as rapid absorption would reduce the effectiveness of these types. Insulin works more efficiently over the entire time it needs to because of the slower absorption rate.
Exercise can increase the absorption rate of insulin. If planning a workout or physical activity, account for these when planning injections.
For example, a baseball pitcher should avoid injecting into their throwing arm. The physical activity can affect the absorption of insulin into the body.
Wait to for at least 45 minutes after the injection to exercise a part of the body that is near the injection site.
Avoid injecting into the same site over and over. This can irritate the skin and underlying fatty tissue.
If this happens, it may increase discomfort and cause other complications. Puncturing the same point every time can lead to hard lumps or fatty deposits developing. This can be uncomfortable and even reduce the body’s effectiveness in absorbing the medication.
When rotating injections, move around within the area to ensure that the injection does not always take place in exactly the same spot.
For example, when taking a night time dose of long-acting insulin, a person might always feel more comfortable injecting it into the thigh. However, they should switch between the right and left thigh each night.
If a person always administers a morning dose of rapid-acting insulin into their abdomen, they should alternate between different areas of the abdomen to avoid repeated injections into the same site.
Ask the doctor any questions about insulin injection, site selection and rotation, and other injection techniques.
In addition, people with diabetes should monitor their blood sugar routinely, as the doctor will advise.
It is important to keep track of blood sugar levels in a diary or notebook for sharing with the doctor. Share any unusual values so that the doctor can adjust insulin dosage and delivery as is necessary.
Read more on self-monitoring glucose levels here.
A person can administer insulin injections into the abdomen, upper arm, thigh, lower back, hips, or buttocks.
Take into account comfort, as injections into some sites can cause pain. Be sure to inject into a pinch of tissue and consider the different methods for injection at each site.
Each site delivers insulin to the bloodstream at different speeds, so consider these depending on the time of day and how fast the body needs insulin.
Avoid repeatedly administering injections to the same spot. Speak to a doctor for advice on switching sites and self-administering.
Insulin is a hormone which helps to regulate metabolism and lowers blood glucose levels.
It is most often prescribed for patients with type 1 diabetes. Sometimes it is also used to treat type 2 diabetes. This would be when other methods have not been able to control blood glucose levels
There are many different insulin preparations available in the UK. There are three main groups of insulins: fast-acting, intermediate-acting and long-acting. Insulin is usually given by sub-cutaneous injection. There are many devices available for administering insulin. They are often designed for ease of administration by patients and carers.
Care planning
You should have a person-centred care plan for anyone using insulin. This should include:
- an assessment of the support a person may need to manage their diabetes care
- the details of the person(s) responsible for providing any extra support
- information to support safe administration of insulin
- information about blood glucose levels monitoring, including the frequency and acceptable range
- what to do if blood glucose levels are outside of the acceptable range
- what the signs and symptoms for low or high blood glucose levels are and the appropriate treatment
- any person-centred dietary requirements.
Monitoring blood glucose levels
A person’s care plan should be clear and document:
- who will administer insulin
- who will monitor blood glucose levels.
Some people can do this for themselves.
Record any actions you need to take to support a person to manage their diabetes care.
Only trained and competent staff should be responsible for administering insulin or monitoring blood glucose levels. Where a person’s diabetes care is stable, a care worker could complete this activity as a delegated task.
Find out more about delegating medicines administration.
Blood glucose levels will determine whether insulin doses need to change and by how much. For people whose diabetes is difficult to control, insulin doses may be on a varying dose scale. Blood glucose levels will determine how many units they take each time.
Records need to show how much insulin has been given on each occasion. District or community nurses may keep their own records. Details must also be available in people’s care plans.
Flash glucose monitoring
Some people monitor their blood glucose levels using a flash glucose monitor. This is a small sensor that they wear just under the skin.
It records glucose levels continuously throughout the day and night.
Whenever necessary people can scan the senor to check their blood glucose level.
Where a person is being supported to use a flash monitor staff should be trained and competent to use this.
Administering insulin
Self administration
Some people will be able to administer their own insulin.
Assess and record the risk to check that they are able to do this safely (a risk assessment). If not, nurses or trained care staff should administer the insulin.
Care staff must receive specialist training to administer insulin as a delegated task . They should be assessed as competent to administer insulin to the named person or people.
If community nurses administer insulin, records must also be available to care home staff
Rotate injection sites
Rotate the injection site to avoid lipohypertrophy. This is also know as lipos - hard lumps that can form if you inject the same place too often.
Common injection sites include upper arms, thighs, buttocks and abdomen.
When nursing or care staff administer insulin, they should record where they injected the insulin each time.
Accessories
A variety of hypodermic needles, syringes, lancets and other accessories can help with administering and monitoring insulin. They are usually available on prescription.
Always measure insulin with an insulin syringe or appropriate commercial insulin device. Devices (such as insulin pens) are marked in units.
Never measure insulin with an intravenous syringe marked in millilitres (ml).
Never use a syringe to extract insulin from pen devices or cartridges. This can lead to serious errors. Find out more in this NHS Patient Safety Alert.
Disposal
Dispose of sharps in a suitable container. Make arrangements to dispose of these containers appropriately.
Find out more about handling sharps in adult social care.
Insulin 'passports'
Insulin passports help reduce administration errors. They provide a record of a person’s current insulin preparations and dose schedule. They also include other patient information such as emergency treatment and contacts.
Low blood glucose - hypoglycaemia
Insulin can cause low blood glucose levels (hypoglycaemia). The timing of insulin administration and meals is important. It helps to avoid fluctuations in blood glucose levels.
Be aware of the symptoms of low blood glucose levels. They can include hunger, anxiety or irritability, palpitations, sweating, or tingling lips. If severe it can lead to convulsions, loss of consciousness, coma and death.
A person-centred care plan should identify:
- what symptoms of a low blood glucose level are
- the actions to take if the levels are low.
Some people might need to use emergency ‘rescue’ medicine or food. For example, oral glucose or glucagon injection, to increase their glucose levels.
High blood glucose - hyperglycaemia
There are several reasons why high blood glucose levels (hyperglycaemia) may occur. For example if a person:
- has missed a dose of medicine
- has eaten more carbohydrate than the body or medicines (or both) can process
- is stressed
- is unwell from an infection
- has been over treated for low blood glucose levels.
High blood glucose levels can cause diabetic ketoacidosis (DKA) which will require urgent treatment.
The persons care plan should specify:
- what blood sugar levels are appropriate for the person
- the actions to take if the levels are high.
Storing insulin
If not stored correctly, insulin products can lose their effectiveness. As insulin is a protein, it may break down if frozen or left out of the fridge for longer than the manufacturer specifies. Medicines stored in a fridge should be between 2ºC and 8ºC.
Find out more about storing medicines in a fridge.
Once the insulin is in use this can usually be stored at room temperature for a limited period. Record the date when you first open or use an insulin product. This helps when checking how long the insulin has been out of the fridge. For detailed information refer to the package/label for each product.
Labelling
Some multi packs of insulin pens are supplied in boxes labelled with the person’s name. Sometimes the supplying pharmacist will label the individual pens. If individual pens are not labelled, make sure it is clear who the insulin pens belong to.
Accurate recording
When prescribing, transcribing or recording insulin do not abbreviate the word 'unit'. Always write it in full. Abbreviations (such as ‘u’) can be confused with a zero (particularly if handwritten). This could have serious consequences.