This app was mentioned in 3 comments, with an average of 1.33 upvotes
Glucosio https://play.google.com/store/apps/details?id=org.glucosio.android
And we are now also beta testing on iOS and web will coming in the near future along with desktop apps!
Disclaimer: I'm a co-founder but have no financial interest since it's developed by a charitable nonprofit foundation we formed.
Edit: We are adding reminders now and specifically the idea you have we will implement
If you are looking for Open Source there is Glucosio
Disclaimer: I'm project leader but do not have any financial interest in the app since it is OSS/Non-commercial
I know this is a bit off-topic but have you tried looking at Glucosio? It's on the Google Play Store and is also open sourced on GitHub.