First thing in the morning, call the office of the doctor who told you your insulin was high. Tell them that you didn't get the instructions you were supposed to get for follow-up care, and you need that information.
They should have referred you to another doctor or a registered dietitian who can help you figure out what diet will work with your exact condition. The doctor's job doesn't end when s/he tells you what's wrong with you; s/he is also supposed to make sure you know what to do about it! But doctors are hurried and pressured, so they don't always remember that step. Sometimes you have to be pushy about it.
In the meantime, this is the link to the main page of the American Diabetes Association. They have lots of good information for you to look at, but you'll need your doctor to tell you whether you should act as if you're already diabetic, or whether s/he has other diet recommendations for you. www.diabetes.org/