Good eating tips for Diabetics?

I am looking for tips or a good website that lists a proper healthy diet for a Diabetic. My father is in the hospital and just had his toes amputated and vascular surgery in his legs, and his relatives are taking him burgers, fried foods, and I want to know is this healthy for Diabetics. I know that he's a grown man and has to make his own choices. But I won't be the one to pump his system with the wrong foods. I would think that Diabetics should stick to eating baked foods, low salt, and limited sugar...anything else? I Appreciate any help given.