FIT file glucose support

I searched through the FIT SDK and this doesn't appear to be currently a field for glucose/blood sugar CGM data, so I was curious if this was something that was currently being planned or underway to add as a standard field?

I'm interested since there has been an influx of recent products for CGM and recently many integrations with Garmin devices (e.g. the Supersapeiens and Dexcom fields) although these all appear to be simply implementing a "display only" with no data recording option. (I guess because there's no appropriate FIT field?) So wondered if this was underway.

(I'm trying to find out if I add CGM support for a device whether there's any better option than just adding a custom developer field or re-using the SMO2 field)

0 Ben FIT over 3 years ago

Connect IQ apps and data fields are not able to write data directly into existing data fields in FIT files. Instead, IQ apps write data to FIT files using Developer Data Fields. It is up to the developer of each CIQ app to decide if they want to write data to the file and then how the data is written.

At the bottom of each app description page is a permissions section, in that section you want to look for "Record additional information into activity files". That will tell you if the app writes developer data to the file. A quick look at the available CIQ Apps, it looks like a few write data but most do not. This is due to privacy concerns.

Reusing an existing field for different data is not suggested. This would also go against the Interoperability and Compatibility section of the license agreement. Instead, you can add a custom message to the file to hold the CGM data, or better yet use Developer Fields (they are not just for CIQ apps.

These articles should get you started.

Encoding developer data
https://developer.garmin.com/fit/cookbook/developer-data/

Decoding developer data

https://developer.garmin.com/fit/cookbook/decoding-activity-files/#developerdata

0 ivor_hewitt over 3 years ago in reply to Ben FIT

Hi,

Yes, I'd also be creating the FIT from another device, but regardless if I use Fit Contributor in CIQ I can tag the field with the corresponding "real" fields - but as I mentioned there doesn't appear to be any fields in the SDK relating to CGM despite this being talked of as being one of the ANT profiles for many years (albeit again there's no documentation for it their either).
(e.g. there's even an icon for it - https://www.thisisant.com/company/activity-icons)

Hence my question, given the recent influx of CGM devices I was curious if there was anything "in the pipeline" or anyone knew if there were any draft fields to use.

As for reusing a field, the point was if I just add a developer field and give it a new name sure I can record it in a FIT file, but then there's nothing that will then display that for experimentation of debugging, if on the other hand I tag it e.g. as moxy or hr, then it will be available to display.

Cheers,

0 Ben FIT over 3 years ago in reply to ivor_hewitt

It is not a requirement of developer data fields to set a native id. "Native Id" is what the corresponding "real" field is called in the SDK. So you can start with developer data and add a native id later on if one becomes available.

For analysis, the FIT CSV Tool will output developer fields and there are a few desktop apps that will parse and graph developer data as well.