You may have a slightly increased risk if you grandmother had type 2. The % I don't know.
more important would be to ask how your parents are doing.
Type 2 can often be prevented or very much delayed through lifestyle measures including
1. Maintaining normal weight
2. Exercising regularly
3. Eating lower carb diet, and most particularly avoiding foods with added sugars and high fructose corn syrup (Ie. sticking to a diet made of whole and unprocessed foods).
Routine screening of both hba1c and fasting blood glucose (ideally on an annual basis) would also allow you to check your sugar levels.
Hope this helps.
No I do not know the %; my assumption is that it must be pretty high