I haven't heard of the connection with diabetes before... but it's something I've suffered with occasionally for a few years. I've a newly diagnosed type 2, but believe that I've been diabetic for a few years, so it would make sense.
As you asked here, i have no great idea with your question. i think they have no connection with the two; because Conjunctivitus only due to the allergic reaction. So it has no connection with diabetic