/etc/sudoers by default has a setting to reset the environment. And also defines a default secure_path which is in effect when you run sudo -E [cmd].
You will need to edit the /etc/sudoers file and add 'env_keep' and mention the variables you want to preserve.
Default env_keep += "PATH"
but before this comment out the secure_path line. Then try your command via sudo -E.
