If you have been diagnosed borderline then that gives you a good opportunity to make some changes to your diet to prevent any further increase in blood glucose levels. I assume your HbA1C would have been somewhere between 42 and 47 mmol/mol as 48 would have given you the diabetes diagnosis.
Many people think they have a healthy diet but if your body has a problem metabolising carbohydrates then some of the things considered healthy are not so.
Bread, potatoes, pasta, rice, cereals, starchy veg and tropical fruits can all be problematic as well as more obvious cakes, biscuits, pastry and sugary drinks. But it is often portion sizes that people eat of those things which are too high. The average jacket potato served in a cafe would be far more carbohydrate than most Type 2 people could tolerate.
Focusing your meals on protein, healthy fats, vegetables and salads, fruit like berries with smaller amounts of the high carb foods should help to get your levels down.
Buying a home blood glucose monitor would help you identify any problem foods, by testing before you eat and after 2 hours aiming for no more than a 2mmol/l increase and no more than 8mmol/l. If so then that meal was too carb heavy.
Have a read of the Learning Zone to give you a better understanding of the condition and please do ask any questions you have.
Welcome to the forum by the way.