How to Create Your Own Hybrid Closed-Loop Insulin Pump System

Type 1 diabetes is an autoimmune condition in which the body becomes confused, destroying its insulin-producing cells. Research suggests that people living with Type 1 diabetes make about 180 health-related decisions every day. So it’s no surprise that Type 1 diabetes is a challenging disease to manage.

Work on do-it-yourself (DIY) systems started as frustration grew over the slow pace of diabetes technology advancements. In the diabetes community, this is better known as the #WeAreNotWaiting movement. By “hacking” existing diabetes tools, this group created simpler, DIY solutions for a complicated disease.

DIY systems are a type of automated insulin delivery (AID) device. While they aren’t perfect, they can help to improve the quality of life for those living with Type 1 diabetes. As they’ve become increasingly popular with users standing by their configurability, others continue to choose FDA-approved devices. Read on to learn more. 

What is DIY looping?

Simply put, AID systems are trying to do the job of a pancreas. They accomplish this by:

• Sensing glucose changes with a continuous glucose monitor (CGM)

• Sharing real-time CGM data with an algorithm (brain of the system)

• Making automatic adjustments to the amount of insulin that’s delivered

While a CGM and an insulin pump can be used independently, they’re even more helpful when they communicate. There are two DIY looping options to make this happen: OpenAPS (Artificial Pancreas System Project) and Loop. Both are open-source instructions. This means that they’re available to the general public to build — but not to purchase. It’s important to learn about both systems before choosing one over the other. 

DIY systems are also known as “hybrid closed-loop systems.” This is because they aren’t fully hands-off systems. They still require actions for meals (carbohydrate counting, giving insulin) and adjustments for exercise. Closed-loop, or hands-off systems, are still under development.

Multiple studies show the possible benefits of using an AID system. 

What is an open-loop vs. hybrid closed-loop insulin pump?

First, let’s clarify a few basic terms:

• Open looping: This is when you use a CGM and pump to loop, but the system needs user input. This means that no actions happen automatically. 

• Hybrid closed looping: This has some hands-off actions. That means the pump and CGM will communicate and make adjustments to keep glucose within a preset range. 

• Closed looping: These systems wouldn’t require user input. These are still under development.

Both DIY systems suggest starting with an open-loop and then advancing to a hybrid closed-loop pump when you’re comfortable doing so. Again, both APS and Loop are hybrid, closed-loop systems and still require user input for meals and exercise. 

There are steps to follow that will help you to understand how your system works and how to adjust your settings. Using a loop won’t simplify every aspect of living with diabetes. You'll still be on the hook for: 

• Filling

• Wearing

• Charging

• Inserting

• Caring for your everyday equipment

What are the pros and cons of DIY looping?

Although there are many advantages associated with DIY looping, there are some drawbacks, too. Let’s take a look at both.

What equipment do you need to loop?

The most challenging part can be getting the right insulin pump for the system you decide to use. The APS system has a flowchart that’s really helpful, as does LoopDoc.

Necessary items include:

• Compatible insulin pump and CGM

• Insulin and supplies for the insulin pump and CGM

• Smartphone 

• Connection device (transmitter) that connects the pump and CGM (RileyLink for Loop or Raspberry Pi for APS, among others)

• MacBook computer and Apple developer account (for Loop)

• Accessory case 

• Battery and chargers for smartphone, insulin pump, and bridging device

What can you customize with a DIY system?

People often choose to DIY loop because settings are more adjustable than FDA-approved systems. Both OpenAPS and Loop have adjustable setup options to choose from. You can find instructions for each system in the links above. 

Why are options important? Because they can help you to get the best glucose results possible. 

DIY customizations include:

• Carbohydrate ratios

• Correction factor or insulin sensitivity factor

• Basal rates

• Duration of insulin

• Target range

• Basal and bolus limits

Can I loop with Type 2 diabetes?

Type 2 diabetes is the most common type of diabetes. It occurs when the body isn’t making enough insulin or responding to it as expected. While the majority of people, 90% to 95%, have Type 2 diabetes — only a small percentage take insulin.

Research suggests that looping with Type 2 diabetes may:

• Improve time in range 

• Decrease the risk of diabetes-related health issues

If you have Type 2 diabetes and have been prescribed insulin, an AID device may be an option for you. Be sure to ask your healthcare professional if closed-loop technology could be a good fit. If it is, you can explore DIY systems or an FDA-approved AID system for insurance approval. 

DIY looping may help to improve your access to an AID system if your insurance plan denies coverage of an FDA-approved system. Most private insurance plans and Medicare cover CGM and supplies. Understanding your cost is an important part of choosing the right technology.

Can DIY looping help lower your healthcare costs?

Not necessarily. All of the supplies needed to support a DIY system can stack up in terms of cost. But not having to purchase a new insulin pump can help. Total costs will depend on what path you take with your hardware choices. 

Regardless of the AID system you choose to build or buy, research highlights their potential for positive physical and emotional benefits.

FDA clearance for mix and match systems

Tidepool Loop received FDA clearance in early 2023, but it’s not currently available for use. 

This long-awaited FDA-approved app will be available through the iOS app store, allowing the user to:

• Choose from a handful of in-warranty, commercial insulin pumps to loop with

• Mix and match looping devices (CGM and insulin pumps) that were once incompatible

• Maintain the ability to customize insulin pump settings from those pre-set by manufacturers 

The FDA-regulated Tidepool app is the first tool to originate from a crowdsourced diabetes solution. 

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Written by:

Jewels Doskicz, RN, BA

Jewels Doskicz, RN, is an Arizona-based registered nurse with more than 20 years of hospital-wide clinical nursing experience. She has spent over a decade in medical writing and editing, with a focus on diabetes and autoimmune disease.

Edited by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

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