Liver disease is not a complication of Type 2 diabetes but kidney disease is not an uncommon complication.
Depending upon a poorly controlled type 2 diabetes, then not taking one's Insulin or exceeding one's carbohydrate intake, if left untreated or unrecognised then one could go into diabetic coma........but this would be extremely unusual.
The same applies to Type1 diabetic.
The only situation that might send a diabetic into coma would be as severe infection e.g pneumonia.
You ask an u usual question and I wonder if you have a specific case in mind?