Hi
@casey jones, as others have said, I have found the best approach is to do a test before eating my main meal (pre-prandial), which +/- equates to fasting/normal blood sugar level (depending on what I've been doing), and then do a test 2 hours after I finish eating that meal (2 hours post-prandial). If my blood sugar level is outside the acceptable threshold after 2 hours, then I do another test an hour later (3 hours post-prandial). I also record the sort of carbs, protein and fats - eg Potato; fish - nothing too elaborate. Every few months I transfer these results to a spreadsheet to observe trends. Obviously, I pay immediate attention to any unexpected bad results in the meantime.
The thresholds I use: post-prandial blood glucose levels should to return to within 2 mmol/L (ideal) or 3 mmol/L (acceptable) of the pre-prandial value, and should be below 8.5 mmol/L. Pre-prandial value should ideally be below 7 mmol/L – but of course it can be influenced by other factors, most typically, having snacked within 2 hours of the test. I obtained these “rules” some time back, so can't reference an authority for the values, but they work for me.
When my control started deteriorating a few years ago, and I had to be less arrogant about being in control, I did what
@everydayupsanddowns has suggested and, for a period, monitored everything that I ate. I worked out the weight of carbohydrate involved in common meals and products and also the calorific content (as, being thin, I need low-carb, high calorie). I also considered the glycemic index of the various foods, as some say this has a bearing on how your blood sugar spikes. I found
https://foodstruct.com/ very helpful, as well as other sources. This was all a bit of a pain, but it helped me adapt my diet. I'm aware there are apps to help with this, but I haven't researched these, having done this "long-hand".
Hope this helps.
Nick