Starting Loop: Build

The goal of this Starting Loop series is to help you decide if you want to build and operate Loop.

The build information is found in great detail at the LoopDocs website:

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 iOS is at iOS 15.1 or higher.  We recommend iOS 17.
  • Check that you have a compatible pump and CGM
  • A radio-link device is required for all pumps except for DASH.  If you need one, check that your radio-link is charged or has batteries (RileyLink, OrangeLink, or EmaLink).  
  • 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 Phone (or radio-link) 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 be updated to be compatible with your phone’s iOS, then you can use either build method.  If not, then the Browser Build method is for you since you just need a browser on any computer or tablet.  We recommend the Browser Build for most new Loopers because it is easy to reinstall when your Looping phone is lost, broken, drowned, or otherwise replaced with a new device.

Browser Build

  • You’ll need a GitHub account in addition to the Check List requirements above
  • Instructions for Browser Build are in LoopDocs

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.

Once you have built and have Loop on your phone

  • Go to LoopDocs Setup for instructions on how to configure your app
  • After finishing the Set up 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. You should also 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.
    • Closed Loop bases it’s predictions (and insulin delivery) on CGM data.  If you have a dodgy CGM, you’ll need to manually test to determine if actual blood glucose is higher or lower than your CGM reading. 
      If actual < CGM, then treat with glucose as needed and use either a Manual Temp Basal or a higher target override.  Manual Temp Basal will deliver a set basal rate for up to 12 hours.  A higher target override can be set above your CGM reading, so that Loop won’t automatically deliver insulin until blood glucose exceeds that the override target; it can be set indefinitely. Whichever strategy you choose, be sure to manually check blood glucose frequently and adjust your dodgy CGM strategy until the CGM readings stabilize.
      If actual > CGM, then manually bolus using the Bolus Triangle in the middle of the toolbar and Open Loop so that Loop will continue to deliver scheduled basal. Again, be sure to manually check blood glucose frequently and adjust your dodgy CGM strategy until the CGM readings stabilize.
      Caution: 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 Apple 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.

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