CREATE USER 'zbx_monitor'@'localhost' IDENTIFIED BY 'mypassword';
GRANT SELECT ON *.* TO zabbix@localhost IDENTIFIED BY 'mypassword';

zabbix_agentd.conf

UserParameter=mysql.ping,mysqladmin -uzabbix -pmypassword   ping|grep alive|wc -l
UserParameter=mysql.uptime,mysqladmin -uzabbix -pmypassword status|cut -f2 -d":"|cut -f2 -d" "