Reuters health has just reported that antidepressant use is linked to diabetes risk.
It stands to reason. After all, if a person is depressed, they already have an altered brain chemistry.
An antidepressant will only alter that brain chemistry further.
It is also possible that many pre-diabetics suffer from depression.

http://www.revolutionhealth.com/news/?id=reut-20080407clin001&msc=a62593