The different Wikipedias offer different stories.
English Wikipedia claims poison as a likely cause of death:
In 1481 Mehmed marched with the Ottoman army, but upon reaching Maltepe, Istanbul he became ill. […] According to the historian Colin Heywood, "there is substantial circumstantial evidence that Mehmed was poisoned, possibly at the behest of his eldest son and successor, Bayezid."
German Wikipedia lists a string of ailments but emphasises that poison seems unlikely:
Mehmed II, who suffered in his last years of life from gout, a great body fullness and edema in his legs, died on May 3, 1481 on the so-called Tekfūr Çayırı, also Hünkār Çayırı near Gebze, when he collected his army for a campaign. […] Suspicions of poisoning on behalf of the Venetians or of Bayezid, who had fallen from grace because of opium consumption, are based on a lyrical insertion in the chronicle of Ashikpashazade, but are not covered by other sources.
Gottfried Benn simply claims that he died of delirium tremens. (Quoting "Genie Irrsinn und Ruhm: Genie-Mythus und Pathographie des Genies" by Wilhelm Lange-Eichbaum; but not fully online)
But then again in Louis de Mas Latrie: "Projet d’empoisonnement de Mahomet II et du pacha de Bosnie accueillis par la République de Venise (1477-1526)" Gênes, 1881 we read of attempts to poison him. His death was ordered as many as twenty times by the Council of Ten between 20 April 1456 and 28 January 1478.
Following the links from the various WP-pages resulted in not much more than already listed there and further research lead equally nowhere so far.
Therefore I have the following question: What seems to be the most likely cause of death? Is there any evidence for Benn's assertion or a source for what seems to be his isolated opinion?