Hi, I don't have diabetes, but before diagnosis and when I'm ill, I get full Technicolor story vivid dreams. And they can be very disturbing and disruptive to your sleep patterns. I'm not too good in the morning after one.
If I'm in control of being in normal levels, I don't get them mostly.
I have been recently because of circumstances, too high, so I had a week of vivid dreams which really didn't help.
Once I realised I needed to get help, and sorted my dietary intake, things have improved.
What I believe is happening is that in REM sleep your brain is trying to tell you to get your blood glucose levels back down into normal levels or telling you to get more glucose. When my blood glucose levels were fluctuating up and down all day, that is when the dreams started.
The only other thing that could be the cause is too much insulin in the blood. Before diagnosis I had hyperinsulinaemia. The worse my health was getting, the more dreams I had.
Hope this helps.