it will be ok with the meds gone. oddly enough, the way Lantus works is better at lower numbers. If he starts at a lower number at preshot, he won't plummet as far. It's really counterintuitive, but one of the sayings here is "shoot low to stay low." That means that when you shoot your regular dose into normal numbers (50-120) the blood sugar will often just stay in a line rather than dropping fast. So a person shooting a 70 might have a 70 still in 4 hours.
In many ways, shooting a higher number "feels" safer to most people, but the truth is there is farther to fall from a high number. As long as you're around to monitor, you'll be able to catch him, but when you shoot a lower number you'll see that he won't drop in free fall like he's been doing.
I saved this post that I wrote to Darin/Charlie about
Shooting Low. It might help explain some of that more fully.
Here's the thing - Webster is still eating dry food (high carb) and getting syrupy sugary meds (high carb) and you're giving him Temptations treats (high carb) and he's on a very small dose of insulin and he STILL got into green numbers today.
When he's done with the meds and the dry food is gone, you'll be able to adjust his insulin to fit his needs.