Hybrid closed loop
A closed loop system involves using an insulin pump that communicates with a continuous glucose monitor (CGM) to adjust insulin levels automatically in response to rising or falling glucose levels. It is sometimes known as an artificial pancreas. The systems that are currently available use this technology but still require you to do a bit of work to ensure you get the right amount of insulin with meals and snacks. This is why they are called "hybrid closed loop" systems.
How do hybrid closed loop systems work?
A closed loop system consists of three linked medical devices that help people to manage type 1 diabetes. The three parts of closed loop system are:
- A continuous glucose monitoring (CGM) sensor that checks sugar levels in the body every few minutes
- An insulin pump that delivers insulin into the body, and
- A digital controller that analyses data from the CGM sensor and instructs the pump to deliver the correct dose of insulin to return blood sugar levels to normal. This computer programme is either contained within the pump itself, or separately e.g. within a mobile phone app.
Pump users will know that insulin is delivered by the pump in two ways i) a basal rate running all the time in the background, and ii) a bolus amount given with food. Closed loop systems can do some of the work in managing blood sugar levels by adjusting basal rates, but they struggle to keep up when glucose levels are rising rapidly. This means that you still need to enter the amount of carbs that you are planning to eat in order for the pump to give the correct amount of insulin.
Advantages of using hybrid closed loop
The main advantages of using hybrid closed loop are:
- Eases the burden of diabetes - research studies have demonstrated that people with diabetes and their families report improved sleep and feeling less worried about the possibility of having low or high blood sugar.
- Improves glucose control - research studies have also shown that glucose control improves in those who start using hybrid closed loop systems, with more time spent in range and less time below or above the target range.
Disadvantages of using hybrid closed loop
Users of closed loop systems have described the following problems, many of which are similar to those experienced when using a CGM device:
- Responding to multiple alarms
- Needing to wear a CGM device
- Problems with CGM sensor not working
- Dealing with other technological problems e.g. pump failure
- Less effective when being used during exercise.
The Digibete app and website contains more videos discussing the advantages and disadvantages of hybrid closed loop systems -
available here. The Scottish Health Technology Group recently reviewed all the available evidence for the use of closed loop systems in T1D. You can read about their
recommendations here.
How do I get access to hybrid closed loop?
In order to get a hybrid closed loop system up and running, you need to have a compatible insulin pump and a continuous glucose monitor that will be able to communicate with each other.
We currently offer 4 different insulin pumps and two different CGM devices, which can be used with the hybrid closed loop systems shown in the table below. The table also shows the main difference between the systems. Please get in touch with the DOT team if you would like more information on these systems or would like to get started on one.
Table comparing the hybrid closed loop systems available within the DOT Tayside service.
