More optimistic note
I think that it is possible to be a vegetarian and a diabetic since leafy vegetables and beans generally are low-starch.
However, i agree with the comments above: your friend should still talk to a dietitian to make sure that they're eating enough low-starch foods and still getting all their essential nutrients. One way to give freedom to your meals will be used the Insulin
based on carbohydrates.
Answer assisted by Emily Lu, Medical Student