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Closed loop systems (artificial pancreas)
Some people with type 1 diabetes use an insulin pump and a continuous glucose monitor that ‘talk to each other’. It does this through a computer programme on your phone or inside the pump.
This is called a closed loop system. It is sometimes known as an artificial pancreas. It can do some of the work for you to help manage your blood sugar levels (apart from you tapping in the carbs from the food you eat).
The doses of insulin your body needs through the day and night to help keep your blood sugar levels stable are released via your pump. Some of these are adjusted automatically in response to your blood sugar levels which are monitored all the time by the continuous glucose monitor (CGM).
There are two types of closed loop systems. The first is hybrid closed loop systems, which are regulated and available to buy. In November 2023, NICE recommended that over the next five years hundreds of thousands of people living with type 1 diabetes should be offered hybrid closed-loop systems. Read the full update here.
The other type of closed loop system is called a DIY system. These systems are developed by people in the diabetes community. They are unregulated and so not available through the NHS.
Hybrid closed loop systems
There are four main licensed hybrid closed loop systems available in the UK on the NHS or for people who can afford to pay for it themselves. The other hybrid closed loop systems available aren't as automated - so you have to do more yourself.
People with type 1 diabetes using a hybrid closed loop system can have a better quality of life, research shows, because of the benefits it brings. And 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 closed loop system work?
When you have type 1 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. So a closed loop system is sometimes called an artificial pancreas or an artificial pancreas system.
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 always supported research into the artificial pancreas.
“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.
“I can’t completely switch off but there’s a reduction in the burden of thinking I have to do. The system can work out complicated factors on your behalf — like how much insulin is 'on board', where your sensor glucose is now, and where it's likely to be in 30 minutes time — then it can make adjustments to help you out."
Different parts of a hybrid closed loop system
There are three parts to a closed loop system.
Not all types of continuous glucose monitors and insulin pumps can work together.
Continuous glucose monitor
A small sensor that sits under your skin. It continuously sends your blood sugar readings to a separate device like a mobile phone or direct to your insulin pump.
The algorithm
A computer programme that reads the blood sugar info and works out how much insulin is needed. The algorithm can be part of an app on a separate device like a mobile phone or may be part of the insulin pump itself.
An insulin pump
The pump automatically releases insulin into your body whenever you need it based on your blood sugar readings (except for mealtimes when the pump still needs info about carb amounts in your food). To work as a hybrid closed loop, it needs to be able to communicate with a CGM sensor, sometimes called a looping, sensor augmented, or an integrated pump.
Benefits of hybrid closed loop systems
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 reduce hypos and lower your HbA1c and risk of diabetes complications.
Research shows the benefits brought by 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 closed loop system for children found nine 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
Why can hybrid closed loop systems make things easier?
You no longer need to do insulin injections for yourself or someone else unless there is a failure of the technology, because insulin is released via the pump. It can help prevent hypos by suspending insulin and prevent high blood sugars 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. If your blood sugar levels go too low or too high, your CGM will sound an alarm.
You’ll still need to carb count and tell the pump about any meals or snacks you are eating. And you’ll need to replace the sensors, pump tubing, and needles according to the manufacturer’s instructions and refill the insulin reservoir on the pump when it is getting low.
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 what food you’re eating 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.
Who might a hybrid closed loop system not be suitable for?
If you’re not comfortable wearing diabetes equipment on your body, a closed loop system may not be suitable for you. And the amount of data about your blood 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 closed loop system unless you have a carer to support you.
Can anything go wrong with a hybrid closed loop system?
It’s important to always carry a back-up diabetes kit with you if you use a hybrid closed loop system. You need to be able to do an insulin injection or a finger prick test if it goes wrong for any reason. For example, the pump might stop working if the batteries need replacing or the tubing becomes blocked. Or you may be unable to get a signal between devices if there are sensor or transmitter issues.
Next steps if you’re interested in using a hybrid closed loop system
Who can get a hybrid closed loop system on the NHS
National guidance has been published in England and Wales on which people with type 1 diabetes should be offered hybrid closed loop, which you can read more about in our news story from December 2023. They have been recommended for some adults based on their current self-management, all children and young people, and all people who are pregnant or planning pregnancy, with a phased rollout of the tech to eligible groups over five years.
In Scotland, they are recommended for people with type 1 diabetes who are struggling to manage their blood sugars, are at a high risk of hypos, have impaired hypo awareness, or are experiencing diabetes-related distress.
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 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 having hypos, you may want to speak to your healthcare team about a hybrid closed loop system.
They can tell you if your insulin pump is ‘loopable’ and can be used for a closed loop system, and your options for a hybrid closed loop compatible pump.
If you’re using a standalone insulin pump issued by the NHS, you may be locked into using it for the standard four year warranty period before being switched to a hybrid closed loop pump.
If you’re already using a CGM on the NHS
If you already have a continuous glucose monitor and wanted to move to a closed loop system, the next step would be talking to your healthcare team about whether you may qualify for one on the NHS.
If you’re self-funding a CGM or insulin pump
If you’re self-funding a continuous glucose monitor or an insulin pump, and are interested in self-funding a hybrid closed loop system, see the information on the systems available for sale.
If you already have a CGM, you may just be able to buy a hybrid closed loop insulin pump. 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.
You may also want to chat about the different systems or find out others’ experience of them by using our online forum.
How much does a 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 continuous glucose monitor (CGM) can cost about £2,000 a year. If you are using a CGM with an insulin pump you may not need to purchase a standalone CGM reader.
You'll also need to change the sensor on your CGM about every 7 to 10 days, depending on which continuous glucose monitor you're using. Transmitters which send the information to the pump cost around £200 to £500 and last between 4 months to a year depending on the system.
Main hybrid closed loop systems available
These are a handful of licensed closed loop systems available in the UK on the NHS or for sale for people who can pay for one. They are sometimes called artificial pancreas systems. They are regulated by the Medicines and Healthcare products Regulatory Board (MHRA).
These four hybrid closed loop systems can do more of the work for you than other systems available. They are usually the ones offered by the NHS.
The first tubeless hybrid closed loop system - Omnipod 5 - is available on the NHS. It works with the Dexcom G6 CGM.
A few 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).
But unlike the hybrid closed loop system, you can’t just plug a DIY closed loop system in and expect it to start working.
You need the technical know-how to build and use a DIY system. Unless you have a good understanding of 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, they should still offer you support to look after your diabetes.
If you have the technical skills you can finely tune a DIY loop system so it’s more responsive to you as an individual. You can ‘train’ your system to respond to what you’re eating. So a DIY closed loop system will do even more of the work for you than a hybrid closed loop system.
