DM vs diabetes mellitus

DM and diabetes mellitus both are nouns.

Word	Noun	Adjective	Verb	Adverb
DM	Yes	No	No	No
diabetes mellitus	Yes	No	No	No

As nouns, DM and diabetes mellitus are synonyms defined as:

DM and diabetes mellitus: diabetes caused by a relative or absolute deficiency of insulin and characterized by polyuria

DM (noun)	diabetes mellitus (noun)
diabetes caused by a relative or absolute deficiency of insulin and characterized by polyuria	diabetes caused by a relative or absolute deficiency of insulin and characterized by polyuria