What is a closed loop system?
Some people with diabetes use an insulin pump and a continuous glucose monitor (CGM) that ‘talk to each other’.
This happens through a computer programme that can be on your phone, inside the pump or on a separate device. This is called a closed loop system.
Closed loop systems can do much of the work for you to help manage your blood sugar levels, also called your blood glucose levels.
When you have diabetes, your pancreas can’t make and release insulin like it should. By releasing insulin whenever your body needs it, a closed loop system works like a pancreas.
Closed loop systems are also known as an ‘artificial pancreas’
A closed loop system is sometimes called an artificial pancreas or an artificial pancreas system.
Some people might find these names give a false impression because it can create the idea that closed loop systems work in the same way as a working pancreas, and that you don't have to do anything. This isn't the case, though, as there are things that you need to do when using the system.
For example, you still need to count carbohydrates in your food and drink and add this information on your pump. You also need to add when you exercise, and how long for, as they can affect your blood sugar levels.
The closed loop systems that are available on the NHS or to buy are called 'hybrid closed loop' systems because they combine automated insulin delivery with the manual parts, such as food, drink and exercise, that you need to input.
You may also see closed loop systems sometimes referred to as automated insulin delivery, or AID for short.
How many types of closed loop system are there?
There are two main types of closed loop system:
- Hybrid closed loop systems
- DIY system - these systems are developed by people in the diabetes community. They are unregulated and so not available through the NHS. Read more on DIY systems below.
Hybrid closed loop systems
Hybrid closed loop systems are available on the NHS, with rollout programmes at different stages across the UK.
They’re also available to buy in the UK, for those that can afford to pay for it themselves.
Research shows that people with type 1 diabetes using a hybrid closed loop system can have a better quality of life because of the benefits it brings.
It can also make life easier for people caring for them. Blood sugar levels may be more stable and there are no insulin injections to do — and fewer finger prick tests.
How does a hybrid closed loop system work?
Your insulin pump releases the doses of insulin your body needs through the day and night, which help keep your blood sugar levels stable.
Doses of background insulin, also called basal insulin, are adjusted automatically in response to your sugar levels, which are monitored all the time by the CGM.
And your meal-time insulin dose, also called bolus insulin, are calculated by the pump when you tell it how many carbs you're eating or drinking.
You can check the amount and agree or adjust the insulin dose before you confirm the insulin to be delivered.
Different parts of a hybrid closed loop system
There are three parts to a closed loop system.
Continuous glucose monitor
A small sensor with a filament that goes under your skin. It continuously sends your blood sugar levels to a separate device like a mobile phone or directly to your insulin pump.
The algorithm
A computer programme that reads your sugar levels and works out how much insulin is needed to keep blood sugar levels in target range.
The algorithm can be part of an app on a separate device like a mobile phone or Personal Diabetes Manager (PDM), or it may be part of the insulin pump itself.
An insulin pump
The pump automatically releases insulin into your body based on your sugar levels, except for when you have food or drink that contain carbs, as you’ll need to input the amount of carbs you’ve had into the pump.
To work as a hybrid closed loop, the insulin pump needs to be able to communicate with a CGM, these pumps are sometimes called a looping, sensor augmented, or an integrated pump.
Not all types of CGM and insulin pumps can work together.
Who can use a hybrid closed loop system?
Hybrid closed loop systems are generally suitable for children and adults with type 1 diabetes, although it will depend on the licensing rules for each system.
These systems aren’t currently available for people with type 2 diabetes who use insulin through the NHS, although we’ve funded research in this area which we hope will help change this.
We've supported research into the artificial pancreas from its early stages of development.
Who might a hybrid closed loop system not be suitable for?
If you’re not comfortable wearing diabetes equipment on your body, a hybrid closed loop system may not be suitable for you. And the amount of data about your sugar levels and insulin doses can be overwhelming so it may not suit everyone.
If you find it hard to do things with your hands, or you have vision problems, you may find it hard to use a hybrid closed loop system unless you have a carer to support you.
Can I get a hybrid closed loop system on the NHS?
In November 2023, hybrid closed loop recommendations were published by the National Institute for Health and Care Excellence, or NICE for short, which said that hundreds of thousands of people living with type 1 diabetes in England and Wales should be offered this technology.
Then, in April 2024, NHS England announced the beginning of a five-year implementation plan identifying and offering the tech to children and young people and eligible adults with type 1 diabetes.
The rollout will prioritise people who are pregnant and all children and young people, with other eligible people being offered the tech within five years.
- Read more about who can access hybrid closed loop systems in England, Wales, Scotland and Northern Ireland.
- Read more about using hybrid closed loops systems during pregnancy if you have type 1 diabetes.
If you’re interested in using a hybrid closed loop system, we recommend discussing it with your healthcare team. You can also chat with others on our online forum who are using these systems to find out about their experiences.
If you’re already using a CGM on the NHS
If you already use a CGM and wanted to move to a hybrid closed loop system, the next step would be talking to your healthcare team about whether you may qualify for one on the NHS.
Find out if you can get a CGM on the NHS.
If you're already using an insulin pump on the NHS
If you’re already using an insulin pump and it’s not helping keep your blood sugar levels in range, or you’re experiencing low blood sugar, also known as hypoglycaemia or hypos, you may want to speak to your healthcare team about hybrid closed loop.
Your healthcare team can tell you if your insulin pump is loopable, which means it can be used as part of an available hybrid closed loop system, or they can talk to you about what options you have for changing to a hybrid closed loop system.
If you’re using a standalone insulin pump issued by the NHS, you may need to continue using it for the remainder of the warranty period (this is usually four years) before being switched to a hybrid closed loop pump.
What if I’m not eligible for a hybrid closed loop system?
We know it can be frustrating if you don’t meet the criteria set out by the NHS to access your tech. It can also be frustrating if you’re eligible under NICE guidelines for a hybrid closed loop system, but your consultant has said this would not be suitable for you.
In either situation, there may be steps you can take.
Self-funding a hybrid closed loop system
If you aren’t eligible for a hybrid closed loop system on the NHS, it is possible to fund one of these systems yourself.
If you’re choosing to self-fund, it’s important you tell a healthcare professional who has expertise in hybrid closed loop systems. They’ll be able to offer guidance and support.
How much does a hybrid closed loop system cost?
A hybrid closed loop insulin pump can cost between £2,000 and £3,000 plus around £1,500 per year for the cannulas, reservoirs and tubing required for its use.
A CGM can cost about £2,000 a year. You'll also need to change the sensor on your CGM about every 10 to 15 days, depending on which CGM you're using.
If you already have a CGM, you may just be able to buy an insulin pump that is ‘loopable’ and can be used for a hybrid closed loop system. If you have a standalone 'non loopable' insulin pump, you’d need to buy a ‘looping’ pump and the CGM system that works with it.
Do get advice from your healthcare team first. You can also check which pump or CGM may work with what you have.
Main hybrid closed loop systems available
These are a handful of licensed hybrid closed loop systems available in the UK on the NHS or for sale for people who can pay for one. They are regulated by the Medicines and Healthcare products Regulatory Board (MHRA).
- Omnipod 5 - a patch pump, which means it has no tubing and uses the SmartAdjust algorithm. It works with the Dexcom G6, Dexcom G7 and the Freestyle Libre 2 Plus CGM. It is licensed for use from 2 years and over.
- Dana i - an insulin pump which works with Dexcom G6 CGM and uses the CamAPS FX algorithm. It is licensed for use from the age of one and over and for use during pregnancy.
- Medtronic 780g - an insulin pump that works with a Guardian 4 and Simplera Sync CGM and uses the SmartGuard algorithm. It is licensed for use for ages 7-80.
- Tandem Tslim: X2 – an insulin pump which works with the Dexcom G6 and Dexcom G7 CGM and uses the Control IQ Technology algorithm. Licensed for use from the age of six.
- mylife YpsoPump - works with Dexcom G6 and Freestyle Libre 3 CGM and uses the mylife CamAPS FX algorithm. It’s licensed for use from the age of one and over and in pregnancy.
DIY closed loop systems
We can’t recommend DIY closed loop systems as they aren’t regulated.
Some people with type 1 diabetes use DIY closed loop systems using algorithms they have built themselves that let an insulin pump talk to a continuous glucose monitor. DIY systems are also known as Open Artificial Pancreas Systems (APS).
You need the technical know-how to build and use a DIY system. Unless you have a good understanding of the technology and operating systems needed, you won’t be able to fine tune the algorithm to your own needs.
These systems are not regulated and often involve self-funding the various pieces of technology to make them work. There are no manuals, warranties or customer support – just an online community.
Healthcare teams have limited knowledge of DIY systems so are unlikely to be able to offer much guidance. But if you're using one of these systems, you should make your healthcare team aware and they should still offer you support to look after your diabetes.
Benefits of hybrid closed loop systems
You no longer need to do insulin injections for yourself or for someone else unless there is a failure of the technology, because insulin is released via the pump.
As the amount of insulin given is calculated more precisely and given more often, this can help keep blood sugar levels more stable. As a result, this can increase the amount of time you spend in your target blood sugar range. This can lower your HbA1c and risk of diabetes complications.
The automatic adjustments to insulin doses mean that if your sugar levels go low or high you no longer need to manually adjust the insulin doses yourself.
Hybrid closed loop systems can help prevent hypos by suspending insulin and prevent high blood sugar levels, also known as hyperglycaemia, by increasing insulin doses.
And you won’t need to do so many finger prick tests as blood sugar readings are monitored by the CGM. Your CGM will still sound an alarm to let you know if your levels have gone too low or too high.
Research shows the benefits brought by hybrid closed loop systems can help give people with type 1 diabetes and people caring for them a better quality of life.
One study testing the hybrid closed loop system for children found 9 out of 10 parents:
- Spend less time managing their child’s diabetes
- Spend less time worrying about their child’s blood sugar levels
- Report less trouble sleeping.
You’ll still need to carb count and tell the pump about any meals, snacks and drinks you are eating and drinking. And you’ll need to replace the sensors, patch pump, or pump tubing, and needles according to the manufacturer’s instructions and refill the insulin reservoir on the pump when it is getting low.
“A closed loop system has improved my life with diabetes. It’s cut out about 90% of my low level dips into hypoglycaemia. And it’s smoothed out some of the irritating drifts in my blood sugar levels.
"I still need to put effort in, for example, carb counting my meals, or switching it to exercise mode, but I don’t have to keep such a close eye on things."
Mike Kendall, Online Community Community Coordination at Diabetes UK, who lives with type 1 diabetes, experience of a hybrid closed loop system.
In research studies, some hybrid closed loop systems have been shown to help with managing glucose levels and improving health outcomes during pregnancy. Read more about the benefits of using hybrid closed loop systems during pregnancy.
Downsides of hybrid closed loop systems
Using technology to help you manage your blood sugar levels is a little like switching from driving a car with manual gears to driving an automatic car. It can take a while to get used to and you’ll still need to keep an eye on things.
As well as tapping in the amount of carbs for the food and drink you’re having, you’ll need to replace the sensors and keep the insulin topped up. And you’ll need to be aware of any drastic changes in blood sugar.
For example, if you do very strenuous exercise or wildly miscalculate carbs, the system may not respond quickly enough. You may need to change the insulin settings manually in these situations.
Help and support with your hybrid closed loop system
You should get hybrid closed loop system training and ongoing support from your diabetes healthcare team.
Pump manufacturers also give support if you need help with the technology or if it breaks, and most have helplines you can call if you’re struggling.
We have more information about insulin pumps, CGMs and other diabetes tech on our online forum – join the conversation.
Can anything go wrong with a hybrid closed loop system?
If you ever experience any safety concerns with your CGM or insulin pump you should report it to the Yellow Card scheme.
You can also follow this step-by-step guidance from the MHRA which will give you detailed information on how to report any safety concerns and what information you need to include.
If the pump you’re using breaks, contact the pump manufacturer straightaway. They will organise a replacement pump to be sent to you.
It’s important to always carry back-up diabetes supplies with you if you use a hybrid closed loop system. For example, you need to be able to do an insulin injection or a finger prick test on a blood glucose monitor if your system doesn’t work, for any reason.
You should also have a supply of long-acting insulin and know what doses you need to take in the event of pump failure.
Unexplained high blood sugar levels
It’s quite unusual to have unexplained high blood sugar levels on a hybrid closed loop system.
The UK Association of British Clinical Diabetologists Diabetes Technology Network (ABCD-DTN) says that unexplained blood sugar levels above 15mmol/mol for longer than two hours could indicate a problem with the cannula or infusion set. If this happens, you should change your cannula or infusion set straight away and check for ketones.
If you have high blood sugar levels, you should speak to your diabetes team for advice on when to check for ketones. You can develop a life-threatening condition called diabetic ketoacidosis (DKA) very quickly if there is a problem with your pump giving you the insulin you need. This is because this insulin in the pump will be short-acting not long-acting insulin.
If you experience high or low blood sugar levels while using your hybrid closed loop system, you may need to treat this differently to how you did before using the system. You can talk to your healthcare team for advice on this, and for advice on sick day rules and ask about having an individual care plan.
Are hybrid closed loop systems affected travelling on planes and going through security checks?
If you’re travelling abroad, it’s a good idea to check your tech manufacturer’s advice on flying with your insulin pump and CGM.
It can also be helpful to contact the airline you’ve bought tickets from, or look on their website, for guidance for people living with diabetes.
Security staff at the airport may ask to see evidence that you need to use your diabetes tech so it might be a good idea to get a letter from your GP that you can bring to the airport.
Not all diabetes tech can go through certain security checks, such as X-ray scanners, at airports so it’s important to speak to your healthcare team and check the manufacturer’s guidelines before you go.
If you don’t want to remove your CGM/sensor/insulin pump to go through a full body scanner, ask for a “pat down” instead.
Please be aware that this may take some time, as a pat down might need to be completed by a specific member of staff, so it may be helpful to factor this into your travel plans and leave plenty of time to go through airport security.
Insulin pumps are safe to use as normal when flying but changes in air pressure can affect the amount of insulin delivered. Monitor your blood sugar levels more closely on flights, especially during take-off and landing.
Read our information on our Diabetes and Travel page to learn more about diabetes technology and airports.
There is a Medical Device Awareness Card you can download, or print, ahead of your holiday, which provides information about insulin pumps for both you as a traveller and for airport security officers.
Can hybrid closed loop systems be exposed to water and hot and cold temperatures?
Depending on which CGM and insulin pump you’re using, there’ll be different guidelines on exposure to water and high and low temperatures.
Read more on our insulin pumps page and our CGM page.
What happens if I am using a hybrid closed loop system and I am admitted to hospital?
If you know you will be admitted to hospital, you can contact your diabetes team in advance to let them know. Or if you’ve been admitted unexpectedly, you can ask the hospital ward staff to let them know.
If you’re admitted to hospital, the hospital staff and the diabetes team will talk with you about whether you should continue using your insulin pump as usual during your admission.
If you’re generally well, you’re able to continue self-management, and there’s a specialist team at the hospital who can provide guidance, you should be able to continue using your insulin pump as normal.
If you’re unwell, your hybrid closed loop system might need to be ‘disengaged’ and changed to manual mode. This means that your CGM and insulin pump will no longer talk to each other, and you’ll need to adjust the insulin pump settings, such as glucose target range and background insulin rates, with support from your diabetes team.
Some people admitted to hospital might be able to continue using their CGM and insulin pump in closed loop mode if they meet specific criteria and under the guidance of their diabetes team. Hospital staff will discuss with you what the best option is for using your closed loop system during your hospital admission.
If you’re very unwell when you’re admitted, your consciousness is impaired, or you can’t use your tech yourself, your insulin pump will be discontinued, and you’ll be given insulin injections or insulin through a small tube called a cannula instead.
Your hospital may not have all the supplies you need, so you, or your family or friends will need to bring these in. For your insulin pump, this will include infusion sets and pump reservoirs.
When you’re admitted, the hospital should prescribe you with the insulin you normally use in your insulin pump. You might also need to bring your own CGM supplies, or have friends and family bring them in for you.
Can you get insurance for your hybrid closed loop system?
Like all types of tech, looking after your insulin pump is important. Because electronic devices are expensive, you may wonder whether to get insurance to cover it in case you lose or break it.
Before taking out separate insurance, it’s worth seeing if you can have it as a named item on your household insurance. This might be a cheaper and simpler option.
