Bull. There is a thing called, I believe, a "functional patent," where, if you combine elements (mechanical devices, etc., not the elements in the periodic table, although I suppose they could qualify as well) in a new way to perform a specific function, you can get a patent for that design. So if your Dr. Deagle has discovered that a mixture of Alpo and horseradish cures diabetes, he can probably get a patent on that combination. It would definitely be worth a try.
Hell, you can even patent genes, for God's sake.
Alternatively, as others have suggested, why doesn't he just release the information and alleviate the suffering of millions, if not billions, of people? A Nobel Prize in medicine would almost certainly be in his future.