My partner is a type 1 diabetic and has missed his 6pm needle, he is feeling very sick and is falling asleep. When he did a finger prick reading it showed up as 'hi' as it was so high it didn't show a number. I am wondering if I should let him sleep it off or if I need to do something?

You need to get him to the hospital immediately!

HOSPITAL NOW. Since he's hyperglycemic he can go in to a comma and die. Do you know how to give him insulin? If you do, I'd give it to him or if he can do it himself... let him. If he doesn't wake up call an ambulance.

But do not let him just sleep. High glucose for a prolonged period, can cause permanent brain damage and death.