OP, I also was induced due to Gestational Diabetes, and was scared about the pain. It was also strange being given a date and going to bed knowing the next morning we would be leaving the house and returning with a baby!
I had a pessary which started contractions immediately (was already 1cm at 37+5). These went on for about 24 hours (nothing major just slightly painful tightening). I went down to labour ward to have waters broken and a bit of a stretch and sweep. That bit was painful but it was over in a second and gas an air helped a little.
Once they'd broken waters the contractions intensified ten fold to the point I didn't know what to do with myself. I begged for diamorphine after 20 mins which left me off my face for about 4 hours. When that began to wear off I begged for an epidural. Turns out DS was back to back.
It did end in twice failed suction and then an episiotomy and forceps then I lost a litre of blood from the episiotomy!
The pain was like nothing I've felt before but I think this was from him being back to back, and I didn't have to have the drip which I think is what people say make subduction so painful normally as they can make the contractions go from 0-100 very quickly.
I believe I was quite unfortunate with my labour, but many people have very smooth inductions.
The pain will come, and you'll have your baby in your arms before long and it's so worth it. My advice would be to do lots of walking once you've had the pessary and to have an epidural before the pain becomes too much.
I was so squeamish at the thought of an epidural but by that point id have done anything for the pain to go. You don't give a shit about being catheterised, about the needle, about anything other than the pain stopping. It allowed me to get some rest before the pushing began.
Good luck, you'll be fine. At the end of it you'll have your gorgeous baby!