I'm no doctor but generally with a pre-diabetes a doctor will prescribe metformin to help and control that also diet and exercise. My wife is a type 2 and her A1c was 6.0. Doctor put her on metformin and told her to follow a low carb diet. If you're not looking to take metformin I would again see a doctor and follow a low carb diet for awhile and do plenty of cardio and let him know your plans. Sucks man to hear that take care and obviously follow up with another a1c test in a few months.
walking and any sort of cardio should be your first daily go to step to lower blood glucose. sitting for long periods is as bad as smoking. diabetics have to keep a daily focus on movement. even nervous shaking your leg is better than nothing.
Check out youtube videos by DR.neil bernard and John Mcdoudall about curing diabetes. I know you asked metformin, but this is good info for diabetics in general.