the antbody levels do not predict/determine the course. selenium can help - the blood sugar question needs more research.. thyroid replacement is based on thyroid levels, not antibody levels.
Treatment will be based on your thyroid hormone levels and not the antibodies. Selenium is reported to reduce TPO antibodies but there is a current literature that is suggesting that Selenium may lead to diabetes. I am someone who takes Selenium.
I have read literature stating that antibodies alone, in absence of thyroid dysfunction, can cause symptoms.
http://www.ncbi.nlm.nih.gov/entrez/eutils/escan.fcgi?db=PubMed&uid=15288851&dopt=Citation&field=Titl...
http://www.jrheum.com/abstracts/abstracts04/2036.html
Good luck!