Some time ago, I did an experiment. I can't locate the post, so no link. I discovered that if I took a glucometer reading after a normal amount of sleep, then went back to bed and slept an additional 2-3 hours, then rechecked my blood glucose, my glucometer reading jumped higher. Thus indicating that too much sleep raises my glucose levels.
Since my struggles with pseudo-narcolepsy, I can't seem to get enough sleep. So I have been further exploring the impact of sleep on my fasting blood sugar. Today I was planning to go to work later than usual because heavy rain were predicted in the evening. I was up later than I had planned. I awoke after 6-1/2 hours, took my glucometer reading, then went back for a brief nap. After the brief nap, I realized I was feeling utterly wiped, so took tonight off & went back to bed. I just re-checked my blood glucose levels. Glucometer reading went from 170, down to 142. So it appears that when I really need more sleep, I should sleep more.