More useful in my view to look at trends rather than just base data and simple average -although a 7 day moving average can also be useful. Easy to do if you have a spreadsheet available. If you don't, download Open Office, its free.
I tested twice daily, before breakfast and before my evening meal. (As my start figure was 14.4, I marked a target level on the graph and I also marked the 4-6 range and 4.5-5.6 range.) My goal was to be below 7 in 3 months. Key the data in 2 streams, no need to date mark but it is useful to have day number to show elapsed time on the graphics.
Select and apply a trend analysis on each data stream. Project the trend lines for the sets of data about 15 days forward. The slope of the trend line shows if you are moving towards or away from the target range, or flattening out. As the data accumulates you can then look at the last 30 days, last 60 days as well as all data graphic. Looking towards a target is more easy to interpret how you are progressing than looking at short term numbers or crude averages.