I've also heard something called Iberogast can help, but I don't know much about that (yet).
Have they found a cause for
the illness yet? Diabetes only accounts for
about 20% of all cases. 36% of cases are idiopathic (me, for example, although I think it's my gallbladder dyskinesia combined with a postviral illness) with up to 1/3 of these being post infectious. (A bad flu can develop into gastroparesis.) The other most common cause is post surgical. Other causes, too many to list.