Based on a 2015 AAAAI review, diamine oxidase test is not helpful in the laboratory evaluation of allergic conditions (the text was edited below):
There is insufficient information to validate the concept of histamine intolerance. Tests that are suggested include histamine infusion, histamine oral ingestion, red wine provocation; plasma histamine quantification; and measurement of the enzymes involved in the degradation of histamine (including Diamine oxidase). None of these can be recommended due to lack of information proving the predictive value of the tests.
Histamine structure. Image source: Wikipedia.