I don't know about all measures taken, but the gluten free meals came with another dish covering the food, signifying to them and us that it was separate. It was also coded on the receipt "C" for which was probably "Celiac".
Be sure to ask for the gluten free menu. There was quite a large offering, so take advantage.
My son was able to get gluten free bread as well, which I believe was Schar rolls, but which he really enjoyed.
We all loved our meals; two gluten free, two "natural" (lol). The lasagne was light and "fluffy" with a tasty ragu. We think it was the same as their Bolognese sauce, which we loved in a spaghetti dish.
The gluten free carbonara and spaghetti with meat sauce were equally wonderful.
This was our favorite meal in four days in and around Verona and Venice. Just excellent. Can't say enough about the service and location. If you have a chance to go to Murano, DO IT. Skip some of the craziness in Venice for a pure treat! Osteria al Duomo is worth it, and more than once, please!
— Very
— Separate gluten-free menu
— Most/All
— Excellent