When 40’s occur at the end of the cycle, it can be beneficial to withhold food and test in 15-20 minutes to determine if kitty is on the rise or hasn’t reached nadir yet.
If they are hanging in the 40s for a while, or if they are still dropping, it is ok to feed a tsp or two of LC and retest. This is very tricky. You want to avoid feeding too much while you’re waiting for them to go over 50, because you don’t want to artificially inflate the number with food.
--- Example: if kitty is 43 and you feed a whole meal, or feed some HC, and the number bumps up to 52, is that the cat’s natural end-of-cycle rise, or is it food spike? What if it is food spike? Then if you shoot the 52, when the food wears off he might drop back to the 40’s (and when insulin kicks in a couple of hours later, you might have a problem). If the 52 is the cat’s natural rise, then he will probably keep rising for the next few hours until insulin kicks in. If you can’t tell whether the number is food spike or natural rise, it’s safest to wait. Your data will help you here. Study the spreadsheet. How much food spike does the cat usually get? How many hours after the shot does the insulin’s onset usually occur in this cat? At what number is the cat likely to be when onset occurs? If the cat does drop, how easy/hard is it to regain control of the numbers? How carb sensitive is he?