I would like to emphasize that although one is under medicines, however, he/she should not stop using herbs or performing the lifestyle and diet changes.
I would be great if one is always following these steps. Please keep in mind that everything you do, you should advise with your doctor because it would be needed to change dose or therapy during the course of treatment.
At the end, to reply to your question. As you may see, there is no precise answer to your question. It all depends on how well one diabetic is reacting to both therapies (allopathy and ayuverdic).
And the only one who can give an exact answer is only your doctor as he/she is following you closely.