Wendy, these are the hardest types of curves/numbers to figure out. It's obvious that his dose needs changing, but which way? In my experience here, conventional wisdom is to raise the dose, but those numbers look almost like the definition of rebound on a long acting insulin. Here is my source (petdiabeteswiki) quoted:
A typical rebound pattern, most often seen with long-acting insulins, is a high, flat, unresponsive blood sugar over a period of days. Sometimes, often when raising dosage, this high flat curve will be punctuated by sudden drops to very low values, (with possible hypoglycemic events) followed by a fast return to high unresponsive numbers. (It's the sudden dip that distinguishes this pattern from inadequate insulin, but it doesn't always happen.)
http://petdiabetes.wikia.com/wiki/Somogyi_rebound
While that 112 is not a "very low" number it was sudden and he did immediately climb back to the 300s and stay there.
If this is rebound, and you raise the dose, his numbers will probably get worse (they won't get better except maybe the second day's numbers, in my experience with Beau), but the drops may become more definitive (Beau dropped to the 30s). However, if you decrease the dose enough the numbers will get better.
If it is NOT rebound the numbers should get at least a little better on a dose increase and worse on a dose decrease.
At this point my gut is saying he is rebounding and his dose may be between .25u and .5u, but your decision is to make a call on the risks of "going the wrong way". I know its really confusing right now. Things to consider are ketones if the dose is reduced and that was the wrong move versus potentially very low numbers if you increase and THAT was the wrong move. Do you leave food down during the day, or can he be fed a snack between +4 and +6? Beau always had food available and they are usually pretty good about eating as their BG drops below 40 or so.
What I think I would do for one of my cats with these numbers is drop to .25u, let that settle 3-5 days, test for ketones, get spot checks as I can and then do another curve. But I have not had any hint of ketones with either of these guys and they both eat well.