Thank goodness he found out! Diabetes must be treated. It is a manageable disease if treated--but a killer if not. He wil need your support, of coruse, but together you can keep it in check. Also, if it is in its early stages, he might be able to manage with just diet and oral meds rather than injections.
Our mother and grandmother had diabetes. It is a serious condition, but thank goodness treatable. Don't let him piddle around, though. Some people (like our mother) think they can get away with playing games with their diet--they can't.
I will send positive vibes your way, too!