Lene said:
The problem is he doesnt seem to care and said he wants to cook for himself as he likes fried food.
Hiya Lene,
Rather perversely, the "two fried breakfasts a day" and his love of fried food, with a little modification, are probably a good start for a low-carb diet, that will help his diabetes control.
Fried egg, bacon, (high quality) sausages, black pudding, tomatoes are all excellent low-carb foods, and are a key part of lots of our diets, and much better for diabetics than supposedly healthy foods like bread, pasta, rice and potatoes. If he enjoys them, I'd encourage him to stick with his two fried breakfasts, and just cut out one or two "high-carb" things, like chips and bread.
As Malc says, if you can convince him to test, then you and he should be able to see for himself which foods are good for him.
Ultimately though, there is only so much you can do. If having both legs amputated hasn't shocked him into dealing with his diabetes, then anything that you can try seems unlikely to help.
Good luck!
Stephen