If it is your first time shooting green, then we will likely suggest that you stall the first time, even if the number is 80-100. That will let you collect data on what your cat will do when you stall. One thing you can do if you are having a low cycle is to get a +10 and +11. Those will give you a good idea of how quickly the cat’s numbers are rising (or not) when preshot time arrives.
Beyond the general guidelines, there are other factors we consider when we are helping someone with a low preshot.
If the low preshot is not part of that cat’s normal pattern or there is reason to think something might be wrong, we will be more conservative.
If the cat is not a food spiker or tends to have an early onset/early nadir then they may not want to shoot as low. If the cat has a late nadir, then they will HAVE to learn to shoot low.
We will also be more conservative in some cases because of the person – if you are not able to monitor then you want to be more careful, or if you are not sure that you can get back to the board to keep us updated throughout the cycle. Trust me, if you shoot low, we will be watching for your updates and we will worry if we don’t see them.
We have to be a lot more careful with the cats who eat only dry food, because they don’t have access to the tools the rest of us use to keep our cats safe.
Also, when it comes to very low preshots, there is an unwritten rule that whoever helps that person shoot low should expect to sit with them through any low parts of the cycle. There have been times when I knew a cat’s number was likely shootable, but I also knew that I could not be around to help if the shot resulted in low numbers later in the cycle. For safety’s sake, if I could not find someone else who would be available to support for the next several hours, I would most likely suggest that the shot be reduced or skipped. I will not encourage someone to shoot low and then abandon them.
There are a lot of other scenarios, and you always want to keep your cat in mind.
Some general rules when stalling (ECID):
** 50s or higher – don’t feed. The number will bump up on its own soon due to the insulin wearing off.
** 40s or lower – you have a couple of choices.
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?
** Test often (every 15-20 minutes, or at most every 30 minutes). You want to catch the rise the minute it starts. With most of our cats, once they start to rise they will really zoom. You want to get the insulin in as soon as possible, because it will be another 2-3 hours before the insulin kicks in and you don’t want to let the cycle get too far ahead of you.
Perhaps the most important guideline in shooting low is that any time you shoot your lowest ever number, you should get a +1 and +2 to give you an idea of how the cycle will go. If the +1 is not higher than PS, or if +2 is much lower than PS, that means “pay attention” over the next few hours. Those tests will also help you become even more data ready for the next time you are presented with a low preshot reading.
Using the overlap by shooting low is a great way to take advantage of Lantus/Levemir’s long, flat cycles, once you have learned to do so safely.
I know I'm not much help right now. 
