How to make etckeeper use the right value for git author & email with apt-get

How to make etckeeper use the right value for git author & email with apt-get

I'm using git with etckeeper.
When I use sudo git to commit changes in /etc/, GIT_AUTHOR_NAME &
GIT_AUTHOR_EMAIL from my env is used (as intended).
When I use sudo apt-get and changes are auto-commited, the local
username@host is used instead.
Why the change in behavior and how can I make sudo apt-get use the ENV vars?