Autocorrect seems to have changed the first word in your post so I'm not sure who has developed prediabetes.
But cutting the carbs a bit has worked for many of our members.
Seeing as the person you speak about is only in the prediabetic range, they might find small changes are enough to drop to non diabetic numbers.
A meter to test before and some two hours after meals can be a great help to find what foods spike their BG.