Missing cat, Minneapolis

He is Grey/Silver with lighter grey around mouth and belly, yellow eyes. Short hair, sleek. 9 years old, medium build, neutered.Collar is dark with tag that says "call my mom" on the other with a phone number. He is unable to eat/digest normal cat food and has a special diet. He is an indoor cat, friendly but can be skittish if approached quickly. He escaped through an open door last night and is likely in the neighborhood somewhere.