If he wants to fix the numbers, it's sort of his thing. It's great that you are helping him and an architectural/ math/ science background would probably be very helpful but, if my numbers are off, I bang away with more insulin. For a long time, I wasn't really organized about it and gained a lot of weight overshooting and eating to keep up but I'd rather do that than run high all the time. That's no fun. I think that he has to make changes. *peeks* if you are in Canada and he doesn't get a ton of support from his doc/ medical providers (or anywhere else, but I've noticed that Canada seems to pose challenges?), he should get on here and post some more specifics and people will probably help him.
I agree with AR. If he is consistently high lately than something in his management is not working or has changed and he needs to figure it out and compensate for it. You don't include any details and it wouldn't make a lot of sense to give you detailed answers anyway. What he needs to do is come on here himself and give some specifics so we can support him in making changes. But he has to want to do that. You can't do it for him. All you can do is be there for him and maybe all you can do right now is take care of yourself so he can do the same.
I can tell you that most of us feel pretty crummy when our BGs get high (generally over 200). You can feel irritable, moody, have a headache, etc. I am definitely nicer when my BGs are in range!
Can you describe a little more about what you mean by "very high?"
Do you have any idea what is going on that would cause these high blood sugars?
It is not uncommon for T1s to go through any number of things that cause blood sugar levels to go higher. Some can develop insulin resistance or just changing insulin needs, which they may or may not be quick to respond to. A looming infection or illness can cause blood sugar levels to go up, as can stress.
And sometimes burnout is the culprit. T1 diabetes is a tough disease to manage. It's 24/7. It gets old after awhile. It's not uncommon for people to sometimes just stop caring, especially when they have been dealing with it a number of years. The worst part is that this can turn into a dangerous cycle (not caring leads to higher BGs which leads to a bad mood/depression which leads to more not caring).
Ultimately, he is in control of his health. You can support and listen, but you can't do the work for him.
Have you had a conversation with him about this?