Byetta came out in the US about 5 years ago, and many users have reported good weight losses with it, but almost everyone suffers from nausea to one degree or another on it.
It came to the UK just over 2 years ago, but was available only through hospitals initially, but has now been released for GP's to prescribe. However, it seems that the GP or practice nurse needs training with it before they can prescribe it. Also, its an expensive drug so some GP's may not be too keen to prescribe unless they have tried other avenues first. I think i just wore my GP into the ground lol.
Im also on Metformin in the form of Glucophage as well as the byetta, the belief is that metfomin/glucophage work very well in conjuction with byetta and my doc was keen to get me on both.
If you google byetta you will find tons of info on it.
Its not all plain sailing though, its a very new drug and there are some possibly negative side effects associated with it. But then, most drugs can have negative side effects, so as long as your GP and mother are happy with any potential risks then she should definately give it a try.