I know that in Islam it is haram to masturbate, even in case a man cannot marry and in case one cannot marry than he has to resort into fasting, for it diminishes sexual desire. But what if the man in question has huge sexual desire, cannot marry in any way whatsoever and he has DIABETES (he cannot fast because of that)???
Madhab/jurisprudence followed: generally none , although I'd personally deem the Hanbali one as the best because it was the madhab of Imam al Bukhari, Ibn Taymiyyah and Muhammad ibn Abd al Wahhab.
P.S: I'm not justifying masturbation forcibly in this case, but I want to know whether the "daroorat" issue applies here
P.P.S advice to those who engage in it. From my experience, I can tell you that, when I was being accustomed to masturbate thrice a day, it rendered me just numb mentally and psychologically, not making me focus on things properly and moreover it made me forget thinks very quickly and often. It harms more mentally than physically, even though there's a great extent in both aspects. Don't masturbate. Even zina, which is a bigger fa7sha, is physically healthier than masturbation because it can be just anatomically and physically similar to sex between married man and his wife (NOTE: I'm NOT condoning zina in any way shape or form, you'll get what I mean if you're mind bearing) (the physical outcome from sexual intercourse between two healthy people of opposite gender and the marriage counterpart of the latter would be the same)