Starting Loop: Build

The goal of this website is to help you build and operate Loop.  There are two primary versions of Loop:  Loop-main and Loop with LnL Patches.  Loop is also referred to as Loop 3 since it replaces its predecessor known as Loop 2.

If you’d like to build Loop, we recommend iOS 16 or higher.  Technically, all you need is iOS 15.1, but you’ll have a much better experience using iOS 16 because older phones that can only operate iOS 15.x are more likely to struggle with Bluetooth and other issues.

Before you start your build, please complete the items on the Checklist.  Make sure to pay particular attention to the Cautions and Future Tasks sections that come after the Checklist. To be successful – you must not skip them.


  • Check that your iPhone or iPod iOS is at iOS 15.1 or higher.  Again, we recommend iOS 16.
  • Check that you have a compatible pump and CGM
  • Check that your radio-link is charged or has batteries (RileyLink, OrangeLink, or EmaLink).  A radio-link device is required for all pumps except for DASH
  • Check that your Apple Developer program subscription is valid and visit the site to make sure no new terms or conditions are pending acceptance
  • Check that you have a plan to deal with data for yourself, your doctor, or perhaps a caregiver
    • If your Looper is a child, consider how you are going to handle interactions with the school nurse and when/if/what you need to add to the 504 plan
    • Make sure you are in a position to keep the school from taking away the radio-link or Phone from your child

There are now two different build methods – Mac Build and Browser Build.  Your next steps depend upon which method you’re using.

If you have a Mac that can operate macOS 13 or higher, then you can use either build method.  If not, then the Browser Build method is for you since you can use a Mac, PC or tablet.

Mac Build

  • Check that your Mac OS and Xcode are compatible with your phone’s iOS.   If you’re using iOS 16 or higher, you will need to enable Developer Mode on your phone.
  • Plug in your phone and use the Build Select Script to build the version you have selected
    • It may take a long time, but Xcode will always finish with a “Build Succeeded” or “Build Failed” message
    • If it failed – read the message – it may be as simple as your phone being locked and needing to be unlocked
    • If it really failed, read the How To Ask For Build Help page
    • If your build succeeded, simply unplug your phone
    • You will get a message that Xcode lost connection with your phone – that is correct

Browser Build

  • You’ll need a GitHub account in addition to the Check List requirements above
  • Instructions for Browser Build are in LoopDocs
  • The disadvantages of this method are that you must rebuild every 90 days (which is much easier than the initial build).

For Both Build Methods

  • Go to LoopDocs Setup App for instructions on how to set up your radio-link, pump, and CGM
  • After finishing the Set up App steps, continue to the LoopDocs Operate section and review the instructions on using your App
  • Leave Loop “Open” until you have adjusted your settings with Loop making predictions and suggestions, but not automatically enacting any insulin dosing recommendations


    • Your previous settings are probably wrong for Loop
      • Your settings were fine for manual pumping and manually correcting every few hours
      • Loop uses a model for carbs and insulin that updates once every 5 minutes based on your CGM readings
      • Start with Loop “Open” and check your settings until you have them close to your desired results
      • It is not uncommon for your Loop ISF (Insulin Sensitivity Factor) to be higher than the CF (Correction Factor) that you used previously
    • Commit to checking into either FaceBook or Zulipchat at least weekly to look for safety-related warnings. If you are not going to check in weekly, at a bare minimum, sign up for the Loop and Learn Newsletter, and read it when it shows up in your inbox.
    • Don’t be afraid to switch between Closed Loop and Open Loop often as you get your settings sorted out.
    • Overnights are often the first part of the day that people choose to run Closed Loop because, with proper settings, Loop will decrease or prevent low blood sugars and have you waking up in your target range. But, jump in the pool slowly.
    • You can use Loop as simply a Pump Controller (MMT) or PDM (Omnipod) to manually enter bolus amounts. When you run Loop “Open”, you can press on the Bolus Triangle (center of Loop toolbar) and it will make bolus recommendations that you can decide to accept or modify.  As you grow comfortable with those recommendations, you can start to run a “Closed” Loop and let Loop do the adjustments to your insulin dosing. Don’t think it is a race to be full-time Looping. You can Open and Close the Loop, watch, adjust, and learn.
    • And, always, if you have a dodgy CGM, Open Loop until stable CGM data is available. If the CGM is giving you bad data, Loop might make bad predictions. This is not a good idea. For example, if you restart your CGM sensors to extend their life, you know that the final days of that extended life can be dodgy.  While you are starting on Loop, you may decide not to do extended sensor sessions until you are confident of your new settings.

     Future Tasks

    • Data for Doctor:  Make a plan for how you will share your data with your doctors! The night before the appointment is too late.
    • Updates!  Make sure your Developer renewal date is on your calendar.
    • We recommend that all Loopers rebuild every 90 days, but for Browser Builders, it is an absolute requirement.


    Please let us know with a post in Loop and Learn that you followed this Checklist and made it into Looping.  OR, if you don’t want to post in public, use the feedback form on this page to let us know.

    We are all volunteers. We’d like to know if our hard work and passion for putting together this information has helped people, or not.

    Skip to content