Diabetes Insulin Pump: How It Works

When you are living with diabetes mellitus (referred to from now on as diabetes), it is understandable that you will want to find the best type of treatment for you, to help you best control the condition and associated risks.

One of the primary aims for those with diabetes is to manage their hyperglycaemia (high blood sugar levels, also called blood glucose levels).

There are various ways that people can do this, including following a healthy diet and exercise plan, taking oral medications or insulin injections, or having an insulin pump.

Insulin pumps are a way of delivering insulin that are far more commonly used by people with type 1 diabetes.

In this article, we will explore what they are, how they work and the possible benefits and drawbacks. If you are interested in finding out more about these devices and if they may be suitable for you – read on!

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What is an insulin pump?

Insulin pumps are small, electronic devices that deliver the insulin your body needs throughout the day and night. This will include the delivery of your mealtime and your background insulin (your bolus does and your basal dose).

The amount of insulin that is delivered will depend on your blood glucose levels and can be controlled by the person wearing the pump (1). Depending on the type of pump you have, this can also be monitored alongside your insulin pump via an additional glucose meter (1,2).

According to the American Diabetes Association (ADA) and Diabetes UK, there are two types of insulin pumps:

  • A tethered pump

  • A patch pump

We will look at the characteristics of each of those a little later in this article. Firstly, however, we will continue to discuss the attributes of an insulin pump.

A modern-day insulin pump is around the size of a mobile phone and delivers insulin continuously under the skin via a small plastic tube called a cannula. The pump is attached to your body, where the insulin is passed into your bloodstream via the layer of fat that sits just below the skin – your subcutaneous fat. This is called continuous subcutaneous insulin infusion (CSII) (3).

The guidance for whom an insulin pump would be suitable for varies, depending on the location. In the UK, the guidance states that insulin pump therapy is recommended as a treatment option for both adults and children 12 years and over. UK guidance recommends that pumps are only suitable for those with Type 1 diabetes, if they meet the following criteria:

  • Attempts to reach target HbA1c levels with multiple daily injections lead to the person experiencing severe hypoglycaemia Or,

  • Their HbA1c levels have remained high (69mmol/mol or above) with multiple daily injections although the person has carefully tried to manage their diabetes.

In the USA, the criteria differ. The American Diabetes Association has some useful guidance on who may benefit from insulin pump use.

If you think you may be suitable for an insulin pump, speak to your specialist healthcare team.

How common are insulin pumps?

Insulin pump use has not only improved since the early days of their use; it has also significantly increased.

More people than ever before are choosing to use insulin pumps instead of the more traditional insulin pen delivery method.

One scientific article in the Journal of Clinical Medicine (2016), quoted statistics that found around 350,000 people in the US to be using an insulin pump. Of these, about 30,000 have type 2 diabetes.

In the UK, the figure stood at 10,345 in 2016-2017. These statistics were obtained from the National Diabetes Insulin Pump Audit report 2016-17, which was published in 2018 (4).

The report was prepared by Diabetes UK and aimed to summarise the information in a way that was more accessible for people with diabetes. It is not only intended for Healthcare Professionals, but instead, is intended for anyone interested in diabetes care. It aims to build on the data available on those using a pump, and ultimately, to improve their quality of care.

In the UK, the proportion of people with type 1 diabetes using a pump varies significantly depending on the area of the country. In some services almost half of those attending a specialist service use an insulin pump, whereas in other services fewer than 5% of people are using this form of diabetes treatment.

The National Diabetes Insulin Pump Audit report also summarised that the following groups of people are more likely to use an insulin pump:

  • Younger people

  • Women: females are higher users of pumps than men in all age groups, except in those aged 70-79 years, where the split is equal. Differences are most marked in the 30 to 39 years age group.

  • Those with lower levels of social deprivation: the number of people using pumps decreases with increasing levels of social deprivation

How does an insulin pump work?

As previously mentioned, insulin pumps are small, electronic devices that deliver insulin. They do this in two different ways:

  • As a basal insulin dose. This can be described as insulin that is delivered in a steady, calculated, and continuous way.

  • As a bolus insulin dose. This is your insulin that is given as a one-off dose, that is controlled by you and delivered around mealtimes.

Basal insulin and bolus insulin doses are delivered through the cannula, into your bloodstream.

This insulin delivery imitates how the body carries out this function in people with a healthy pancreas.

Within an insulin pump is the main pump unit, which holds an insulin reservoir. The reservoir is most commonly attached to a long, thin piece of tubing with a needle or cannula at one end. This is called the infusion set (1,2,3).

One study conducted in 2013, in Perth, Australia, showed that insulin pump use led to more effective control of blood glucose levels than insulin injections. Complications were also fewer in number and admissions for diabetic ketoacidosis (DKA) were less than half than they were for those using multiple daily insulin injections.

Throughout the study, 345 young people were followed for seven years. These young people were on pump therapy and were matched to a group of young people who were using insulin injections instead.

Both groups had their glycaemic control monitored, and for the group of young people on pump therapy, severe hypoglycaemia episodes decreased by more than 50%. This is compared to the group of people using insulin injections, whereby hypoglycaemic incidences increased.

Conclusions from the study included that not only can insulin pumps help young people achieve better glycaemic control, in the long run this may decrease their risk of diabetes complications. Experts also stress that education and specialist nursing support are essential for this group of people and should be delivered alongside insulin pump therapy.

Another study of interest was the REPOSE study. The REPOSE study was published in the BMJ in 2017 and compared the effectiveness of insulin pumps with multiple injections, amongst adults with type 1 diabetes.

Groups were either assigned to the pump group, or the group continuing to deliver their insulin via multiple daily injections (although the participants had not displayed any interest in one form of treatment over the other).

Both groups also attended an accredited training course, called ‘Dose Adjustment for Normal Eating’ (DAFNE), and were followed for two years. One of the main objectives of the study was to measure improvements or changes in HbA1c. Other markers that were measured included body weight and insulin doses.

Interestingly, whilst both groups showed long lasting decreases in their HbA1c, very few participants achieved results as recommended by key guidelines.

Decreased episodes of severe hypoglycemia and improvements of psychological measures were also seen in both groups. In conclusion, insulin pump therapy as opposed to the use of multiple injections did not improve glycaemic control.

The presence of structured education was believed to be the reason behind significant improvements in control for those with type 1 diabetes, in both study groups.

Whilst an insulin pump can work with a continuous glucose monitor (CGM) to monitor your blood glucose alongside, the device itself does not measure your blood sugar levels. With a CGM, you can check your blood glucose readings at any time. You will be alerted if your blood glucose levels are too high (hyperglycemia), or too low (hypoglycemia).

How is an insulin pump worn?

Insulin pumps are worn differently, depending on which type pf pump it is. Tethered pumps have another small plastic tube connected to them, that is attached to your cannula. The cannula is inserted into the subcutaneous tissue, so that the insulin can be absorbed gradually into the bloodstream.

The main difference with a patch pump, is that they do not need the tubing to deliver insulin to the cannula. As such, a patch pump attaches directly to the skin. Usually people choose to place them on their stomachs, arms, or legs (1).

Insulin pumps can be worn discreetly, for example by tucking them in the waistband of your trousers, putting them under a shirt or in pockets. You can also get cases to hold your insulin pump, that look like a mobile phone case.

Many people choose to wear their pumps with pride, and why not! Living with diabetes is nothing to be ashamed of and should not need to be hidden.

Types of insulin pumps

As previously mentioned, there are two types of insulin pumps:

  • A tethered pump (the most common type of insulin pump)

  • A patch pump

In this section of the article, we will look a little further into each type.

A tethered pump uses a fine tube, which connects the pump to the cannula. A tethered pump is typically worn either in a pocket or clipped to a belt, although you can be creative with how to wear yours!

In comparison, a patch pump does not have any tubing, or it has a very short tube only. Typically, a patch pump is stuck to the skin using tape and is connected directly to the cannula.

Aside from these two broad types of pumps, there are several different brands available on the market, including:

  • Medtronic insulin pumps (e.g. the Medtronic minimed pump)

  • Roche insulin pumps (under the Accu-Check brand)

  • Tandem insulin pumps

  • Omnipod insulin pumps (under the Ypsomed brand)

You can read some more about the different types of insulin pumps that are available here.

What are the benefits and drawbacks of using an insulin pump?

Despite the good treatment outcomes for many who use an insulin pump, the approach is not for everyone. Arguably, as with all areas of healthcare, one-size-does-not-fit-all.

For some people, the technology can be too complex, or they simply may not like the pump being constantly attached to them. On the other hand, they have been found in some research to significantly improve adherence to treatment goals. The National Diabetes Insulin Pump Audit report (2017-2018) found that:

  • Around 9 in 10 people reached their treatment goal of reducing hypos after starting to use an insulin pump.

  • Around 7 in 10 people reached their glucose control goal after starting to use an insulin pump

The next section of the article will allow for a summary of the benefits and potential drawbacks of using an insulin pump (5). Weighing up these different factors can support you to decide if it is the right form of treatment for you.

Benefits of using an insulin pump

  • More flexibility – e.g. in what, how and when you eat

  • Individualised – you can tailor your insulin more easily when you exercise, including before, during and after

  • Blood sugars are more likely to be in your target range, and more frequently.

  • Most people with an insulin pump have fewer episodes of both hyperglycemia and hypoglycemia

  • Better accuracy – e.g. when working to bring down hyperglycaemia

Drawbacks of using an insulin pump

  • Like any change in treatment, it will take some getting used to, and this can be challenging.

  • You will always need to have your pump attached to you and can only take it off for short times, e.g. swimming or showering.

  • You will still need to inject additional insulin sometimes

  • There is a (small) risk of infection from the cannula, and/or irritation from the site where the pump is connected to your body

  • It takes some time to learn about your pump and become familiar with usage. You will need to demonstrate competency and understanding before you are given a pump by your healthcare team.

What other treatments are used to manage diabetes?

An insulin pump is just one form of treatment for the management of diabetes. As previously mentioned, there are several other treatments that you may choose, or be recommended to try out, by your specialist diabetes team.

Some of the other treatments include:

  • Diet and exercise. This may include modifications to your existing lifestyle and diet, increasing exercise levels or trying specialist diets such as a low carbohydrate diet or a very low-calorie diet. Note that whilst diet and lifestyle modifications may benefit many types of people, they are not appropriate forms of stand-alone treatment for people with type 1 diabetes.

  • Bariatric surgery (weight loss surgery)

  • Oral medications

  • Insulin injections

  • Artificial pancreas

  • Pancreas transplant


Whilst the evidence supporting the efficacy of insulin pumps is mixed, there are indications that those who wear one have better glycaemic control and meet their treatment goals with more ease.

This is possibly more meaningful in younger people and should be considered alongside structured education about insulin dose adjustment.

Aside from glycaemic control, the convenience of having a pump can bring significant quality of life improvements to some people who are living with diabetes. It vastly reduces the need for multiple injections and allows the wearer freedom to pre-programme their insulin doses if they are in a typical routine.

Yet, they are not going to be suitable for everyone. Some people may not enjoy being connected to a machine; or may find the devise uncomfortable. If you are interested in finding out more about insulin pumps, or your eligibility for one, talk to your specialist diabetes team.

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  1. Diabetes UK. Insulin Pumps. Online. Available at: https://www.diabetes.org.uk/guide-to-diabetes/managing-your-diabetes/treating-your-diabetes/insulin-pumps#how%20to%20get accessed on 11/7/2020
  2. American Diabetes Association. Insulin Pumps: Relief and Choice. Online. Available at: https://www.diabetes.org/diabetes/medication-management/insulin-other-injectables/insulin-pumps-relief-and-choice accessed on 13/7/2020
  3. McAdam, B, H, and Rizvi, A, A (2016). An Overview of Insulin Pumps and Glucose Sensors for the Generalist. Journal of Clinical Medicine. 2016 Jan; 5(1): 5. Published online 2016 Jan 4. doi: 10.3390/jcm5010005
  4. Diabetes UK: National Diabetes Insulin Pump Audit: what are the outcomes for people using an insulin pump? A summary report of the National Diabetes Insulin Pump Audit for England and Wales 2016–17. Online. Available at: https://www.diabetes.org.uk/resources-s3/2018-12/Insulin_%20Summary_v4.pdf accessed on 14/7/2020
  5. Insulin Pump Therapy. Online. Available at: https://jdrf.org.uk/information-support/treatments-technologies/insulin-pump-therapy/ Accessed on 11/7/2020

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