My Mr. B is diabetic, my Oliver is not and is in excellent health. My vet said that Oliver can eat the Purina DM without any problem. When Mr. B is sleeping or in another room, I'll give Oliver some non diabetic canned as a treat. I'd have your friend check with her vet to ask if the healthy kitty can eat the DM. If not, or if he won't eat it, I'd feed them in separate rooms. And the board that has been mentioned, www.felinediabetes.com is a terrific site for advice and support!!