I think technically the lag can be 20 minutes or so, but in my experience it's more like 10 minutes (important to note, it's not constant, it sends data every 5 minutes), and of course depends on what the glycemic index is, how much fat/protein, stuff like that. If you check out a receiver, it's more useful for seeing trends over 3+ hours. there's a screen that shows you trends over 1hr, over 3hrs, over 6hrs, 12hrs and 24hrs. I find the 3 and 6hr trends to be most helpful. It's not to take the place of your meter, just another useful tool.
