How do other caregivers handle being up most of the night and not being able to get any rest?

Mixed up sleep patterns seem to go with dementia unfortunately, but if he is having lows through the night that isn't normal, he needs to work with his doctors to get better control of his blood sugars. As for the rest of it - this sounds like it may be a difficult habit to break but I would limit his intake at night to tiny snacks (better for his diabetes too) and ask about something that could help him sleep - this may not be a typical "sleeping pill", my mom's life changed for the better when she was given an antidepressant.

My mom had a brief period of time where her evening meds made her restless, and she would be up until 2 or 3 in the morning. I had to be up with her, because she would fall otherwise. When I mentioned it to her doctor, she told me I had to hire a night nurse, because I couldn't stay awake 24/7 to watch her. Thankfully, her meds were changed and she started sleeping through the night again. But, if you want to keep your husband at home, maybe look into a night nurse? Or discuss it with his doctor.

Sleeplessness by the caregiver is a major reason to start looking for a care facility for their loved one. It's very important that you keep your health as his primary caregiver. Not getting sufficient sleep jeopardizes your health and makes you more susceptible to health issues of your own. Sleeplessness, along with wandering and other symptoms, was one of the reasons I sought a new "home" for my wife.