Phone and watch compatibility, in plain terms

Many CGMs and insulin pumps now work with a phone app, and some show readings on a smartwatch. Whether your phone or watch works depends on more than just the brand. This guide explains what actually determines compatibility in plain terms.

Compatibility is a specific list

Device makers test their apps on certain phones and certain operating system versions, and publish a list of the ones that are supported. A phone that isn't on the list may work, or it may work badly, or stop working after an update. For anything you rely on for alerts, stay with a phone on the list.

The operating system version matters most

The operating system is the phone's main software, such as iOS on an iPhone or Android on many other phones. A new version can change how background apps and Bluetooth work. Some device makers recommend checking their compatibility page before you install a phone update, and some suggest turning off automatic updates for that reason. When a big update comes out, wait for your device maker to confirm it's supported.

Android phones vary more

Android phones are made by many companies, and each one adjusts the software. That's why compatibility lists for Android are usually phone-model specific. Battery-saving settings on some Android phones can close diabetes apps in the background, which can stop alerts. Your device maker's app guide usually explains which settings to change.

Watches

Some systems can show CGM readings on a smartwatch. Sometimes the watch shows what the phone app sends, so the phone must be nearby. A few can connect directly. Check exactly how yours works before relying on your watch for alerts, especially overnight.

Before you buy a new phone

Look up your CGM's and pump's compatibility lists first. Make sure you know how to move your app and account to the new phone without losing readings or pairing. Keep the old phone charged until the new one is fully set up.