How often readings update, and what it costs your battery

Where the delay comes from

Garmin sets a floor on how often a background app may run, around five minutes, and the sharing services add their own delay of roughly a minute. A wrist value a few minutes behind your phone is the system working as designed.

• The sensor to your phone. Libre 3 and Dexcom stream continuously; Libre 2 depends on how your phone is receiving.
• Your phone to the cloud. The sensor's own app uploads on its schedule, not on demand.
• The cloud to your watch. GGlance fetches when you open the glance, and when Garmin wakes it in the background.

Getting the freshest possible value

Open the glance. That triggers a fetch immediately rather than waiting for the next background window. If you want the current number before a workout, that is the way.

Battery

The work per refresh is small: one request, a few kilobytes, no GPS and no continuous Bluetooth to a sensor. The watch is not maintaining a connection to anything extra, which is what usually drains a battery.

In practice the cost is low enough that most people never notice it against everything else the watch is doing.

Common questions

Can I make it refresh more often?

The background interval is set by Garmin, not by the app. Opening the glance always fetches immediately.

Does it use mobile data?

A little, through your phone. The requests are small, a few kilobytes each.

Does it work during a workout?

There is a separate data field for the in-workout view, so you can keep the value on screen while recording an activity.