You test for ketones so if he developed DKA, you could catch it early. (
http://en.wikivet.net/Diabetic_Ketoacidosis) Usually it results from too little insulin, in appetite and an infection. It is unlikely Nolan would have it, but if you'd reduce the insulin a smidge, it would just be wise to get the tests.
If it were me, I think I'd take the spreadsheet to the vet and ask her how she thinks he is doing. A blood glucose test at her office will not give you much information as he is likely to be stressed and that will likely heighten his numbers. As long as he is eating and seems to be feeling okay, I don't know what other tests I'd want done.
Just for reference; we generally think a cat is regulated if they are in the mid 200s at preshot and then drop at nadir to double digits, but not below 40 which is approaching hypo territory. He is usually in that range at preshot (maybe a little high) and in blues at nadir, so he could drop a little midcycle. So the first goal is regulation. Then, if you want to push toward remission, you start tweaking the dose to try to get him in lower yellows at preshot and safe greens at nadir. Some people don't want to push toward remission early on or can't, because of their schedules. One of the other measures is the renal threshold. The thought is if the cat stays below the 250-280 range, his pancreas can heal.
You might look for a few other flavors of low carb he will eat. The fish flavors are usually the lowest, but most people limit them to a couple times a week. Not only is there the issue of mercury (just as with humans) but sometimes they get hooked on fish and won't eat other proteins. If your feeding shedule works best for you, I'd stick with it. Remember, this is not an exact science. So many things affect the numbers - from an upset tummy to seeing a squirrel outside to a satisfying poo.

Your job is to go with the flow and try to adapt to his patterns, when you can discern one. :mrgreen: Often cats are higher at night; they usually eat less and have less activity - both of which might change the numbers.
I think you both are doing fine. See what the vet says and maybe make some tweaks, if you are comfortable with them.