We're currently aware of an issue with the Guardian monitor uploader app for Medtronic data to Nightscout that some users are using. Whilst this app is in no way related to us, we are working closely with the developer to resolve this issue.

The uploader does not apply a proper UTC offset value in its upload to nightscout, which in turn means that all values are treated as being UTC. This means that any blood glucose values uploaded via this mechanism may appear several hours in front or behind your local time depending on your offset to UTC.

Nightscout applies front-end timezone conversions and stores all data as UTC relative, however, we store data with a UTC value and its UTC offset so that we can display data in the user's local time irrespective of where you are looking. This is important for people who may be having their data reviewed by others but also allows mobile app users to look at activities and glucose data in the other users local time rather than being relative to the onlooker.

We hope that guardian monitor app will be updated soon to resolve this issue and correctly store UTC offset values based on the uploader's local time zone.