Welcome, and I'm astonished your doctor would medicate you when you are pre-diabetic. Do you know what your HbA1c figures are?
As to improving it, look at the low-hanging fruit first. Sugar / syrup / honey and things containing them (cakes, biscuits, 'full-fat' soft drinks, beer) are all things you can eliminate. So are bananas. And reduce your portions of carbs - pasta, bread (all types), rice (all types), potatoes and other root veg, cous-cous etc. As you are pre-diabetic that might be all you have to do. Suggest with pasta you weigh a typical portion and reduce by 1/3 to 1/2. Bags of dried pasta tend to recommend 100g (before being cooked) per portion, I found 50g was quite enough.