My husband just found out he was a diabetic last year, and we made an AMAZING apple pie for Thanksgiving and it turned out great (in Canada we celebrate Thanksgiving in October, so it's already come and gone for us).

I also used the recipe on the Crisco box for the crust (have for years) and it turned out great. Doesn't have any sugar in it, but she will still need to portion control as it's carbs and fats (all pie crusts are).

For the filling, I simply mixed my apples with a bit more flour, butter, cinnamon, and a few tablespoons of Splenda instead of sugar. Once I was done with the filling and the crust, I sprinkled another teaspoon of Splenda on the top.

Check out your grocery store -- I find that Splenda works great as a sugar replacement in most baking recepies. It measures just like sugar. You might also want to check out their website for a few other dessert recepies. I'm sure that your grandmother will really appreciate the kind gesture!