I choose to live and enjoy life. Thus I do dive
That said, I have been refused service from dive shops when on vacations (Aruba., St. Lucia and a few pothers.) As a result I now have a don't tell policy. while that does sound bad it is just the way I must behave.
On the safer side. My wife also dives, I would not dive without her on a vacation. Thus if there is a issue she would be able to at least report what was going on. When I dive locally. There is no need for my deception as others will know about my condition.
I have read the guidelines and while it was once considered unacceptable to dive there is now guidelines that say it is ok to dive, and for the most part I agree with them.
1) No Decompression dives. This is a big one, since if I do start to get ill, I can be on the surface rather quickly with little concerns for DCS.
2) Start the dive with slightly high Blood suger. Diving just like any other sport will tend to lower blood sugars. A slightly high Blood sugar for limited times will not cause any major issue. However a low bloodsugar can be a major issue above or below water.
In addition I always take a can of Regular Coke with me. That way if I feel low when I get back to the boat, I have a quick sugar source.
I personally have always been able to tell when my Blood sugar is low and thus I have never blacked out. If I did not have a good sense of a low, I am not so sure how I would feel about diving.
Legal disclaimer
All this said. I am not a Dr. Therefore I do not recommend any of this to other diabetes. This is simple the sharing of one persons believes, right or wrong.