Ask him out go on your date and then bring it up in conversation. I agree with the above people if he doesn't understand or get it or cringes... He is not worth it. But, maybe if you tell him in a way that he will understand that it wont be such a big deal for him. Are you on shots or a pump.
If you are on shots it may be a little more difficult for him because a lot of people are queezy when it comes to needles. but thing is if he isn't comfortable you don't have to do it in front of him.
If you are on a pump its just a matter of pressing a button and checking your blood and you can also do that discretely as well.
This is why we need more diabetes awareness so people can understand that umm we do this to live, it isn't a joke and without taking our insulin or take care of ourselves we die bottom line.
For instance, my 3 yr old cousin walked in on my when i was changing my insulin pump and he asked what is that. So I tell him, that is my medicine. He says why do you need medicine? I said so I don't get sick and have to go to heaven. He tells me I don't want you to go to heaven take your medicine, Gina.
This is a 3 yr old, if he can understand so can everybody else. He even asked me if he can press the button to give me medicine, of course I did not let him but I did think that whole conversation was pretty adorable. Maybe a bit off topic but I thought I would share.