Welcome to the forum. Prediabetes will have been diagnosed because your HbA1C result is between 42 and 47mmol/mol so depending on how close to the top of that range will determine how much work you will need to do from some modest changes in lifestyle to something a bit more substantial.
It is all about reducing your intake of all carbohydrates not just sugar. Many people manage to pull their glucose levels back by those dietary changes and lose weight if needed
I could go into a lot of detail but I found this link explained everything in terms of a low carbohydrate approach
https://lowcarbfreshwell.com/