I'm going to be compeltely honest. For me, Gastric Bypass was never really an option. I'm terrified of surgeries and really wouldn't be ok having a sugery that seems quite a bit more complex than Lap Band.
If I were diabetic, however, I might have to do some more research. I know a gentleman who used to work with me who had lap band and developed diabetes after the surgery. On the flip side, however, I also know a person who had lap band a year ago and has since stopped having to take meds for her diabetes.
If I were you, I'd get a second opinion. Your doctor might be completely accurate in his suggestion, but it's important to realize that gastric bypass is much more expensive than lap band, more perminent, and non-adjustable. But I hear it also produces faster results.