You will be able to get the juice down if you do everything they tell you to. I take things very slow and just in case I have extra swelling, I wait a few extra days before transitioning to firmer foods after a fill. Also, when I do have a low and I JUST had a fill(this actually happened last night), I add a few spoons of sugar to some juice and sip it. It has worked wonderfully and I understand the fear but it will be ok.
I have lost about 70lbs and coming up on my 1 year on the 31st. I just got a fill because I have only lost 7lbs since August. It will be harder to lose as a diabetic but you can do it. I let my sugar levels run a little high, 130-160. That way, when I work out, I'm not forced to drink a sugary drinks and it's been easier maintaining my sugar level this way. My A1c is 7.0 and now that I've had the band for a year I'm more comfortable with lows.
Let me know about any question I can answer