Definitely speak to a nutritionist if you can as there is sometimes conflicting info out there and it can be tough to know which way to go.
Common advice for prediabetes does seem to be to get your carbs from low GI, high fibre foods. Typically that involves wholemeal, plant-based sources:
There are also studies suggesting that a low GI diet doesn't necessarily work unless the diet is healthy overall:
So focusing on adding more variety and quantity of fruit and veg, while relying on low GI carbs as opposed to added sugars, is probably better than simply thinking of it in terms of replacing your carbs.
Also, more on general healthy eating but related to diabetes and high cholesterol, these two sources may be handy:
Stanford have a free Introduction to Food course with a basic overview of healthy eating and cooking (including some recipes).
Canada's food guidelines recommend making half of your plate fruit and veg, with the other half split between protein and wholegrain carbs.
Good luck, hope you find lots of delicious and wholesome new recipes to try!