Yes, you will have to transition to this diet. Introducing your cat to a new diet is like releasing fish in a new tank of water. You cannot just throw them in; you will have to do it slowly. For your cat, you have to make a gradual transition as well, otherwise, it might end up having an upset stomach. For the transition, mix the GlucoSupport with its current food in small amounts. Over the next week, keep increasing the amount of the GlucoSupport, and decrease the amount of the old food. Slowly, you can stop mixing the old one and carry on with just the newly introduced meal. Talk to a vet if you are confused or if your cat still gets an upset stomach despite the slow transition.