I learnt a little a few years ago while setting up monitoring and building a "Parakeet" [0] for a relative. I think the Nightscout foundation [1][2] should be a good start. I believe they are very active in their Facebook group.
[0] https://jamorham.github.io/
[1] http://www.nightscoutfoundation.org/
[2] http://www.nightscout.info/