Some diseases, yes; people do this all the time and it is called "running a fever". Fevers are not induced by the disease; they are a strategy you use to kill the disease.
Cancer or diabetes, no. Diabetes is not even a "disease" in the sense of an organism that can be alive or dead.
Cancer or diabetes, no. Diabetes is not even a "disease" in the sense of an organism that can be alive or dead.