I have a diabetic friend. He wants to eat vegetarian. How to do when everything vegetarian is basically carbs?

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.
Agree w/ Dr. Pizzo. Agree with dr. Pizzo. Be sure that it is a dietician (who has taken tests and has a license issued by the state in which he or she practices) and not just a "nutritionist" (who is unlicensed and has no state regulated training or testing.).
Vegetarian. Your friend has to have a long talk with his doctor or dietician prescribing the diet to be sure it is healthy for him. With diabetes one does not have the leeway to try different diets without professional assistance.