'Eat to your meter' is all you need to do.
Your spiking foods will be different than mine and only a meter will tell you which ones you need to avoid.
In addition to Asok, Google search the difference between simple and complex carbs. We need carbs for energy. Learn, understand, and apply why simple carbs should be avoided and why complex carbs should be increased in ones diet.
Being prediabetic means you have a very good chance of reversing yourself back to normal. To do this one MUST adhere to lifestyle changes; proper nutrition, maintain proper body weight, and perform daily 30 minute physical exercise. Ignore one defeats the others.
Do yourself a favor, go to your local pharmacy/drug store/WalMart and purchase a home glucose [blood sugar] test meter. Read the instructions carefully. Post back to this thread if you have further questions or concerns. Good luck.
When I was first diagnosed, I was lucky to have a sit down with the registered dietician attached to the health care team. For males limit carbohydrates to 60 per meal. It sure worked for me.