His most important work was in practical medicine, especially diet and nutrition, but he also wrote the first systematic textbook on animal anatomy.
[3] He was the inventor of the Spoon of Diocles, a surgical instrument for the extraction of weapons or missiles such as barbed arrowheads that were embedded into the body (Greek: κυαθίσκος τοῦ Διοκλέους).
[5] There is a letter in his name addressed to king Antigonus, entitled A Letter on Preserving Health (Greek: Ἐπιστολὴ Προφυλακτική), which is inserted by Paul of Aegina at the end of the first book of his own medical compendium, and which, if genuine, was probably addressed to Antigonus II Gonatas, king of Macedon, who died in 239 BC, at the age of eighty, after a reign of forty-four years.
[6] It resembles in its subject matter several other similar letters ascribed to Hippocrates, and treats of the diet fitted for the different seasons of the year.
His fragments have been recently collected and translated in English by Philip van der Eijk, with a commentary in a separate volume.