For many people, the fasting numbers and your HbA1c go bad only after a long period of time with bad blood sugars. If you are going high after meals you may have what is called “Impaired Glucose Tolerance.” Until you have “Impaired Fasting Glucose” your fasting numbers and HbA1c may still look good. You could ask your doctor for an Oral Glucose Tolerance Test (OGTT) and if you have a blood sugar of 200 mg/dl 2 hrs after taking a 75g glucose load then you are technically diabetic no matter what you A1c says. You can also give yourself the test at home. For my description of how to do this you can read how I did it in early 2010 during what I can only term as a honeymoon.
ps. If you bring test results to your doctor showing that you are diabetic according to the published guidelines, your doctor will be hard pressed to just pass off your concern.