Have you ever read up on motivational interviewing? It's a technique used in the behavioral health field and can be very helpful with non adherent patients.
"Mr Jefferson, you listed all of the reasons why you don't watch your carb intake and I understand that's it's really difficult to do it. But what good things could happen if you did control your glucose levels?"
Also, speak with the patient in his or her own language...if the person doesn't understand medical jargon, don't throw it around as if you are intellectually superior. I'm sure the patient could teach you about his profession! (I'm not saying you're doing this, I'm just throwing it out there."
And, validating his or her feelings/rationale, et al, as well vs dismissing them. So, when a patient lists a negative feeling towards a lifestyle change, or medication or diagnosis, don't begin a response with "at least," or "but." First, acknowledge that the person's feelings are valid.