Shannon, I haven't used Novolin, but I have read that food needs to be on board before an injection.
http://www.felinediabetes.com/FDMB/threads/beginners-guide-to-novolin-humulin-nph.186097/
From the Beginner's Guide to Novolin:
I
t's a good idea to feed your cat an hour before giving insulin. This is to ensure there is food in the cat’s system for when the insulin starts to work, and to help ensure that the BG doesn’t drop too fast or too low. Not all cats will experience a fast BG drop with N/NPH, but until your testing data shows otherwise, it is wise to assume that this may be the case with your cat.
Is there any possibility that you would consider a different insulin for Biscuit? Novolin is less expensive certainly, but it's a very harsh, fast acting, and doesn't usually last the 12 hours between shots. I realized there is always the issue of expense and Novolin is better than nothing.
I just looked at your spreadsheet and the BG doesn't seem to be coming down that much from the reds and mostly pink BG levels. You might talk to the vet about alternatives. We can help with suggestions for cost saving if you decide on a "depot" insulin like Lantus, Basaglar or Levemir. Prozinc is also an alternative, it works like Novolin..and "in & out" insulin, but it's gentler and longer lasting than Novolin.
Good luck with the vet visit today. Please come back and tell us what vet says and you decide to do for Biscuit.