I have an libreoffice spreadsheet which records date/time, bg, reading type (fasting, pre-prandial,...), hours since eating, what I ate, what exercise I did, general comments, remarks and questions (may make these a separate column in next sheet so I can extract them easily). I then have a set of columns that integrates the readings against mins at that reading to give a closer average as I tend to take several readings when I am higher than lower. From this I then estimate HBA1C values etc...
I then have several graphs so fasting against weight loss against time, bg against time etc... It is interesting that when I hit 15% of original body mass reduction my fasting variance around their mean become almost non-existent (.2 either side) whereas before that point it was up to .8 either side
I have been considering writing it all into a java program instead of a spreadsheet as I find many of the current free ones do not give you much information other than a graph
Oh I am so sad