What Is An Insulin Pump & How Does It Work?

If you’ve been newly diagnosed with g type 1 diabetes and you are thinking about using an insulin pump, you’ll probably want to know more about this type of insulin replacement therapy and how it works. 

In the article below, we take a closer look at insulin pump therapy, how an insulin pump works, and the advantages and disadvantages of using one.

What is an insulin pump?

An insulin pump is a device powered by a battery that administers insulin via a thin tube inserted beneath the skin, allowing the insulin to be directly introduced into the person's bloodstream [1,2, 3]. This occurs dually — as a steady basal rate with small portions of rapid-acting insulin, and bolus insulin, which refers to individual, one-off doses taken at meal times. The pancreas produces insulin, the hormone responsible for maintaining balanced blood glucose levels [4, 5].

In people with diabetes, insulin is either not produced sufficiently or does not work properly. By mimicking the natural process of insulin delivery, insulin pumps can help people with diabetes regulate their blood glucose [3, 6]. 

Insulin pump therapy, or continuous subcutaneous insulin infusion (CSII), is generally used to manage type 1 diabetes [1, 2]. However, the use of insulin pumps for people with type 2 diabetes is on the rise globally [1].

How does an insulin pump work?

A traditional insulin pump delivers rapid-acting insulin through a small catheter or tube [1]. The small tube is placed under the top layer of the skin, usually on the abdomen [7], and secured with adhesive [1]. 

The tube is called a cannula, held under the skin and called an ‘infusion cannula’ or ‘infusion set’ [1]. 

The tube connects the pump to the infusion set, which infuses insulin into the tissue under the skin [1]. The infusion site is typically on the upper arm, abdomen, lower back, or upper thigh [3].

Some insulin pumps, called ‘patch pumps', [1, 7], do not require a tube and stick directly to the skin. Insulin is also delivered through the infusion cannula, but these patch pumps are wireless, tubeless, and controlled remotely [1, 7].

Insulin pumps deliver insulin in one of two main ways:

• Small, set, continuous infusions throughout the day and night. This is called basal insulin delivery  

  The other way is called bolus insulin delivery, and it refers to extra, one-off doses of insulin that a person with diabetes may require to cover after meals or as a correction dose to keep their blood glucose in check [1].

Most insulin pumps contain a bolus calculator that works out a recommended bolus dose using the current blood glucose levels, the total grams of carbs consumed,  the remaining insulin from previous bolus doses and an individualised setting to calculate if a correction dose needs to be added [1,7].

The advantages & disadvantages of insulin pump therapy

Although commercial insulin pumps were made available in the 1970s [1, 8], it took three more decades for the benefits of this new technology to become widely popular [1]. 

The potential benefits of CSII became clear after the Diabetes Control and Complications Trial (DCCT) Research Group published a report in 1993 [8]. This landmark clinical trial showed that intensive insulin therapy is important for preventing diabetes complications [1]. Since then, insulin pump therapy has advanced to help patients achieve tight glycaemic control while minimising the risk of hypoglycaemia [1].

What are the advantages of an insulin pump?

There are many advantages of insulin pump therapy. These include:

• Insulin dosing is more precise, flexible, and involves fewer injections [1, 8]. The doses of insulin are easily adjustable throughout the day [1, 8]. This improved dosing makes it easier for people to take control of their diabetes management[1]. 
• With insulin pumps, there is a lower risk of hypoglycaemia at night [8].
• CSII may also offer mental health benefits [7]. Some studies have reported insulin pump users had better moods, lower stress, and improved self-confidence [9].
• People living with diabetes who use insulin pumps also reported more energy, better family relationships, and the ability to perform better at work [7].
• Some studies have suggested that insulin pump therapy may be helpful for young people with type 1 diabetes [10]. The use of insulin pumps was linked with better metabolic control in this population [6, 10].
• The risk of severe hypoglycaemia or diabetic ketoacidosis is lower in people who use insulin pumps [6, 10].
• A recent study has shown decreased cardiovascular mortality among people with diabetes who used insulin pump therapy. Insulin pump use is associated with less variability in blood glucose levels and improved quality of life [6].

These are some advantages of using an insulin pump, but it is also important to be aware of the disadvantages and potential risks. 

What are the disadvantages of an insulin pump?

There are several concerns about the use of insulin therapy. These include: 

• Potential problems may arise if the infusion cannula is not changed appropriately. The cannula needs changing. Every 2–3 days [3, 7]. The cannula may dislodge, or lumps of fat or scar tissue may form under the skin where the infusion cannula is placed [7]. A blocked cannula or one that leaks fluid from the infusion site may also cause problems, such as interruptions in insulin delivery [3, 7]. 
• Localised skin infections — which can cause inflammation, soreness, redness and swelling [8] — may occur at the infusion site but are rarely serious [7]. 
• Problems may arise around the technical function of insulin pumps, such as mechanical malfunction, infusion set failure, blockage or kinking in the infusion set, and issues with alarms (when used in conjunction with CGM) [1, 2, 8]. 
• Because an insulin pump delivers smaller amounts of insulin, the risk of diabetic ketoacidosis (DKA) is greater if the insulin delivery is stopped for any reason (e.g. if the pump stops working or another illness interferes with its use) [7]. However, studies show that insulin pump therapy is associated with lower or similar rates of these complications compared with other therapies [3, 7]. This may be because people with type 1 diabetes who undergo CSII monitor their condition very well [7]. 
• Education regarding the risk of DKA with insulin pump use is vital to avoid this complication.

Other potential disadvantages of insulin pumps:

• Insulin pumps are more expensive than MDI [8, 11]. In some countries, the high cost may be a deterrent for people who do not have medical insurance [2].
• Some people may find an insulin pump difficult to wear [11] or dislike feeling ‘attached’ to it [8]. 
• Starting an insulin pump requires training[8]. Therefore, highly motivated, tech-savvy patients are generally the best candidates to use an insulin pump. 

Weighing up the advantages and disadvantages can help you decide whether you would like to try insulin pump therapy. 

The future of insulin pumps

Overall, the use of insulin pumps is increasing rapidly, particularly among people with type 1 diabetes. A large registry of over 100,000 people with the condition found that its use has increased from 1% to 53% over 20 years [6].

The number of people with type 2 diabetes who are turning to insulin pumps is also increasing [1]. The technology is vastly improving, as continuous glucose monitoring (CGM) systems are being integrated with insulin pumps [1, 4] to provide a seamless and more effortless experience. 

These innovations are reshaping how we think about diabetes and its management. Such therapies can improve people’s quality of life and empower them to better manage their diabetes [6].