With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnatInterfaceTable
cnat Interface Table
1.3.6.1.4.1.9.10.77.1.1.4
This table holds information regarding the interface on which NAT is enabled.
Back to CISCO-IETF-NAT-MIB MIB page.
IPHost Network monitor allows you to monitor cnatInterfaceTable on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.