Help please

The DSN at your or your Dad's surgery should be able to supply pamphlets which will describe the way carbohydrates affect type 2 diabetes. But, honestly? your Dad will get more help from you and your loving concern. Good luck with helping your Dad.

It's a difficult situation that you find yourself in, but all is not lost. As a Type 1 you already have the knowledge and understanding of how foods (Carbs and Sugars) effect the blood glucose levels, so this is great.
If you are responsible for caring after your father, then you can control what he eats and change his diet over a period of time gradually cut back on the Carbs and Sugars and supplement this with Fats, so that he doesn't realise what's going on or feel hungry eventually weaning him over to the LCHF diet.
You need to be diplomatic and careful, so as to not antagonise him or any good work that you do will be lost. Incidentally most medications that a Type 2 diabetic would use (unlike most insulin's) are generally slow acting and take many hours often days to become active, so for this reason it is often better to measure B/G levels before and then again 2 hours after eating so as to work out what foods/drinks are best to keep the resultant rise within a 2.0 mmol/L level.
Incidentally a good book on foods and portion sizes is the Diabetes UK book "Carbs and Calls"
You don't say if he is confined to a wheelchair only that he has difficulty in walking. If he is able to then any form of exercise can be most beneficial, and what comes to mind is possibly gardening, particularly if you have raised flower beds, where he could use his upper arms effectively in planting, pruning, hoeing and what ever else. If this is not possible it might be worth encouraging him to take up a hobby that indirectly exercises his upper body, possibly picture painting, jigsaws, model making in fact anything that moves his upper limbs will help benefit him and keep his brain active as well - The television certainly won't do that.
It will be a long, slow process, and you must take each day as it comes. Don't attempt to change him and everything in one go as it will take some time. There will be some set-backs along the way but over time with a careful approach you should be able to take control of the situation and he will ultimately have a much better life.