These are the *current* maintainers of Dia:

Hans Breuer
E-mail: hans@breuer.org
Userid: hans

These are the previous maintainers of Dia:

Lars Clausen
E-mail: lars@raeder.dk
Userid: lclausen

Name: Cyrille Chepelov
Email: cyrille@chepelov.org

Name: James Henstridge
Email: james@daa.com.au

Name: Alexander Larsson
Email: alexl@redhat.com