Which Hybrid Closed Loop Therapy System is right for me?

Hybrid closed loop therapy

by, Alicia Downs RN, MSN, CDCES

Hybrid closed loop therapy (HCL) is an incredible new tool for diabetes management. 

We can improve time in range and dramatically reduce hypoglycemia. One would hope that this improvement in management can come with reduced work and vigilance on the part of the user; that we would be able to think about and interact with diabetes less, reducing the physical and psychosocial burden of life with diabetes. However, getting on board with the correct system to meet your specific needs is vital to succeeding with HCL technology. A misstep can lead to a burden, being turned off to technology, and most importantly greatly increase the risk of diabetes burnout.

I’d like to share my top 3 questions when helping a patient find the right system for them (let us never forget that clinicians are not here to assign systems to patients based on their preferences or how easy or hard they are for the clinic to work with. The clinician has to deal with it for a moment, the user has to live with it 24/7/365 for 4 years!)

First Question: How involved do you like to be in your diabetes management?

If you like using multiple profiles, or temporary basal rates to actively manage your diabetes needs this is a major decision-making factor in what system will work best for you.

HCL algorithms fall into three categories: 

  • Algorithms based on Total Daily Dose of insulin (Omnipod 5 and Medtronic auto mode) These systems offer simplicity of use and the Omnipod system has no tubing. However, users who use temp rates to gain tight control over things like hormone changes, wide swings in physical activity or even food intake may struggle with these systems a great deal as the user’s range of impact on insulin delivery is largely restricted to adjusting targets.

These systems are also going to take time to “learn”, so they do not tend to work well straight out of the box. They take time to become more effective, so the user has to be willing to have some rocky blood sugars for a couple of weeks or so. These systems are not great to change to if life is rocky or stressful.

  • Algorithms based on user’s programmed basal rates and sensitivity(Tandem Control IQ) These algorithms allow the user to change, more dynamically, how aggressive the system is by setting multiple profiles with differing basal rates, carb ratios, and correction factors that can change how aggressive the system responds. This allows us a more robust control of varying metabolic needs to maintain tight control. Because this system predicts and responds but does not “learn” blood sugar needs it is an ideal system for those whose insulin needs may vary widely for situations such as steroid use, strong variations in stress or activity levels, or even for those who wish to practice periods of intermittent fasting.
  • Algorithms that work based on user settings (Loop/Open APS/AndroidAPS, etc). These systems are for those who desire and are knowledgeable enough to control all factors of their algorithmic adjustments. Because they are not FDA approved, they cannot typically be taught in clinic settings, so ensuring that the patient has strong education support in use of their system is key.  These systems allow the user to completely control all aspects of insulin delivery, however, the change in paradigms of thinking about insulin is being delivered may mean a larger learning curve. These systems are NOT a silver bullet to “fix” blood sugar or management struggles.

Next question: Do you use extended boluses a great deal?

In this are algorithms split in two. Those that allow extended bolusing (like Tandem Control IQ and Loop/Open APS) and those that do not (like Medtronic Automode and Omnipod 5) For some this impact may be minimal. You may not be using extended bolusing at all, in which case any HCL can help with post-meal management. Others may rarely extend more than 1-2 hours (like kids who tend to have faster digestion times) However, for those who eat high fiber high protein diets, who have GI complications or gastroparesis the inability to extend a bolus can be problematic and may require interventions like split bolusing that may add burdens to diabetes management.

Not to be overlooked question: How often do you lose your phone?

Yes, controlling one’s pump remotely sounds great! And having your diabetes world in the palm of your hand has a lot of benefits. HOWEVER, someone who loses their phone may be left with no way of bolusing or pausing/reducing their insulin delivery if they are using a patch pump with no buttons.

The Medtronic pumps have an app that allows the user to see the pump status and BG, but the app in no way controls the pump or CGM. The Tandem pump has an app that allows for viewing and bolusing of the pump. The CGM can also be interacted with via the Dexcom app on a smartphone. However, without the phone, the user still has full functional access to their pump directly.

Omnipod and Loop, on the other hand, are entirely controlled by their apps. Some Loop users are still using it with an older model Medtronic pump, in which case they can bolus from the pump, and then once they find their phone, the app will read the insulin history in the pump and adjust accordingly for what was given when away from the app. If Looping with Omnipod and the phone is misplaced, the basal will remain running at the set basal profile dose but will not adjust without the Loop algorithm assistance. The user also will not be able to bolus until they find their phone OR take an injection in the interim.

The Omnipod 5 does not allow any bolusing, user-based suspending, or other change to how the system will deliver insulin without the control app in range. However, since the algorithm is built into each pod, which communicates with the Dexcom CGM independent of the phone app, the system will continue to adjust basal insulin without the controller in range.

But knowing whether you’re someone who’s going to succeed with a system that requires having your phone nearby at all times is key! If your kid has trouble remembering to put on shoes before they dash outside to play, a system that requires that they remember their phone may not be a good fit.

An important question to prevent burnout: How much do alerts or alarms irritate you?

As people with diabetes, we have a very love/hate relationship with our tech. We love the freedom, confidence, safety, and empowerment of alerts. However, we also hate having our lives interrupted, our anxiety triggered, and yet another meaningless task added to our very busy lives when the alerts are too frequent or demanding.

The Medtronic system is certainly the most alert-heavy system on the market right now. From CGM calibrations to BG requirements to maintain Automode, High and low alerts, and system max/min alerts, the user can expect to get 4 or more alerts, even on a day when blood sugars are “perfect”.  The Loop system is not particularly alert-heavy since the Loop system has user-set maximums and minimums. However, when you do get an alert, you have to be able to troubleshoot the problem. This can be a barrier for some users. You may not get a lot of alerts, but with loop just tapping “ok” to ignore the alert and make it go away is not an option.

When Loop says there is something wrong you need to stop and fix it. For very savvy “loopers” this is not an issue, but for someone with limited ability to stop and deal with an issue, or limited tech-savvy, this can be added diabetes stress. The Tandem system has a minimum of system alerts, and the recent update has even reduced those further. The System will alert if an autobolus over 200 remains high for over 2 hours to notify the user that they may benefit from manually bolusing. It is also important to either complete the bolus process or exit out properly to avoid “incomplete bolus” alerts becoming frustrating. The Omnipod system has minimal alerts for the system. Users may want to adjust their CGM high alerts while the system is “learning” to avoid excessive alert fatigue. The system app/ controller has also had some issues for early adopters with system errors and system updates causing some level of alarm and confusion.

Asking these important questions as well as inquiring about, activities, and desired control levels are key to individualizing HCL selection.

Because the system that may bring liberation and renewed health to one may bring depression and unforeseen hazards to another. As always, never judge someone based on their management choices, and don’t push your preferences on others. We all benefit from having as many options as possible.