ADCYAP1 and diabetes mellitus: Consistent with such protective function, its potential therapeutic role has also been demonstrated in a model in vitro of DMO, hence showing that PACAP is able to also prevent the disruption of the BRB, mainly by modulating the expression of important tight junctions such as zona occludens-1 (ZO-1) and claudin-1, both essential for the proper functionality of the retinal barrier during diabetes [72].