I use an excel spread sheet and have done since 2014. I designed it myself.
All my meter test results are on there, plus BP, cholesterol & lipids, liver & kidney functions, full blood counts, vitamin and mineral test, weight, HbA1cs, Libre data, and food diary (although I got fed up with this and stopped keeping it in October)
I have graph data for all my meter tests split into fasting, before each meal, and after each meal at different times (1 hr, 90 mins, 2 hrs, 2.5hrs and 3hrs. ) plus bedtime.
At the moment I am having a testing holiday. I stopped on 10th November but am using a Libre. I only use my meter at the moment for some comparison tests with the Libre.