On CentOS, you can encounter the following behaviour when configuring an nrpe plugin with sudo:

Given that check_exim is defined as follows, in nrpe.conf:
And given (for completeness) its relative /etc/sudoers line as follows:
Then the problem is in the requiretty options in /etc/sudoers, enabled by default on CentOS. Simply comment it as follows:
After that the plugin should work as expected: