Necessity truly is the mother of invention. And nobody invents quite like tech gurus in the Silicon Valley.
From a PERFORMANCE perspective, Loop offers many advantages. The target glucose levels are customizable by the user – including a temporary target increase (for exercise) and decrease (for pending meals) to minimize the magnitude of the post-meal peak. Loop allows the user to modify suggested bolus doses for both meals and corrections. And speaking of corrections, Loop applies the user’s customary correction factor and target settings in making dosage recommendations. And then there’s the fan-fav feature: With Loop, you program everything directly on your phone!
Most notable, in my opinion, is the fact that Loop makes proactive adjustments instead of waiting for the blood sugar to start going too high or low. It bases this on active insulin (including bolus and basal insulin) as well as active CARBS – something truly unique to this system. When entering carbs for bolus calculations, Loop asks approximately how long it will take your food to digest (2, 3 and 4 hours are common entries). This is essential for determining whether the insulin-on-board will be offset by the carbs-on-board. All of this is displayed clearly on the app’s status screen, along with a glucose projection covering the next 3+ hours.
When determining basal delivery, Loop utilizes the user’s prior basal settings as a starting point. This is a key feature, because it can prevent overnight and between-meal rises/falls rather than waiting to fix them once they take place. The basal adjustments made by Loop can be much more robust than those made by commercially available systems. The magnitude of the adjustments is limited only by the user’s setup preferences, and there is no limit to the duration of the adjustments.
The customizable nature of Loop and the aggressive nature of the algorithm produces glucose control that is tailored to the user’s preferences… which in most cases means “very tight.”
Loop does a nice job of keeping alarms and alerts to a minimum. It more-or-less runs in the background, and only alerts the user if it has lost the sensor signal or has not been functioning for at least 20 minutes.
Loop currently accepts data from Dexcom G5 or G6. G6 is considered by many to offer the best combination of accuracy and ease-of-use of any CGM on the market. Being a non-regulated product, Loop can be adapted rapidly as newer and better products come to market (essentially as soon as the volunteer software developers can add a new “branch” to the program code). No need to go through months (or years) of product testing and then more months (or years) waiting for the FDA to approve the updates.
Loop can generate reports (Nightscout is the primary program), but you’ll need decent tech skills (or someone with such skills at your side) to set this up and read the reports.
For all its strengths, Loop was never run through vigorous usability testing. It doesn’t come with a nice set of instructions. Or professional training. Or 24/7 phone support. Many of the advanced features in the app are difficult to locate. Those who choose to use an old Medtronic Paradigm pump (as opposed to OmniPod) must endure the outdated nature of the pump and lack of a warranty. If something goes wrong with that pump, you’re basically S.O.P. until you can track down a suitable replacement – and that’s getting harder all the time as the availability of Loop-compatible Medtronic pumps shrivels up.
Then there’s the hassle factor. In addition to wearing a pump and sensor, Loop users must have their app-containing phone handy at all times and carry the RileyLink device to enable communication between components. And yes, the RileyLink requires daily (or nightly) charging. Cost-wise, users will incur a few hundred dollars per year out-of-pocket (for the Riley Link and Apple software developer license) in addition to the usual expenses for pump and CGM supplies. For those who use the OmniPod as their pump, coverage may be available through one’s pharmacy benefits. This can reduce out-of-pocket expenses and may allow users of tubed pumps to switch to OmniPod and begin using Loop even while their existing pump is still in-warranty.
Perhaps the biggest hurdle to Loop use is the initial setup. It is NOT for the technologically challenged. In addition to having the right kind of computer for building the app, you will need many hours, significant patience and attention to detail in order to follow the online instructions for “building” the app and installing it on your iPhone. Even after everything is set up, there are dozens of picky little problems that can keep Loop from functioning properly. Most can be fixed easily by the user, but some may require the assistance of the great and powerful Loop Facebook Group.
Overall, for those who can get past the initial setup, Loop offers superior glucose control with minimal work/effort/sacrifice on the user’s part.