Fasting of 107 is a little high. <99 is normal.
One test is not enough to DX diabetes.
Many feel that the fasting is the last thing to show a problem. test 1 hour after your biggest meal of the day. That is a better indication of the health of your pancreas.
As for diet, carbohydrates raise BG (blood Sugar) ALL carbs raise BG. whole grains raise BG slower but they still raise BG
Low carb diet (avoiding all added sugars, restricting grains and starchy vegetables, limited fruits), high healthy fats, proteins and plenty of non-starchy vegetables.
Exercise daily, at least 30 minutes of aerobic exercise. Add in strength training sessions if you can.
All of these will help.
Get a blood sugar meter and test 2 hours after eating a meal to see if your blood sugar is on target (at least < 140, even better < 120, ideally < 100). This will allow you to see which foods normalize blood sugar and which raise it too much and need to be restricted / avoided.
Hba1c of 5.5 gives you an average blood sugar of about 118. This is higher than normal. So definitely you are 'prediabetic'., However, I believe diabetes is like pregnancy, you either are or you aren't.
But it is still 'mild' and by catching and managing it early you should do well.