The a1c of 8 is really high, and an average blood sugar of about 200. Normal is 5.0 or less and an average blood sugar less than 100.
Have you been tested for type 1 diabetes / insulin deficiency? Particularly considering that you have already had diabetes for 8+ years. If you have type 1 and/or are insulin deficient, then injected insulin is required for treatment.
In any case, considering your sugar levels are so high, it would be best to discuss with your doctor about stopping gliplize and taking insulin instead.
Do you follow low carb diet. Would also recommend you look seriously into eating low carb, moderate protein and healthy fats to also help control blood sugars.
If your current doctor will not work with you to get your hba1c down to more normal levels, seeking a second opinion may be recommended.