His lawyer, Steve Cullen, said that was his downfall, when he referred a patient to another doctor who had been a student at the time and recognised his name.
Krishnan gave Middlemore references from Auckland doctors who did not exist, and also faked an email from a non-existent Medical Council staff member.
The hospital declined a request to be interviewed and had not clarified exactly what checks were done on Krishnan.
In a statement it said it had undertaken a thorough review of its vetting processes and made improvements.
“The review has provided us with a level of confidence that the processes we have in place will prevent such an incident happening again,” a spokesperson said.
It apologised again to all the affected patients but said none had been physically harmed.
At the sentencing, Judge Nevin Dawson said Krishnan had applied for jobs as a doctor at other clinics but did not get them.
One thought his CV was odd.
Another, an Auckland dermatology clinic, turned him down last August because by then he was in the news for his Middlemore offending.
Cullen said his client had a “bizarre compulsion” to try to work as a doctor.