By that time, she was estimated to have taken more than 5000 vials, worth more than $7000.
She was able to access the store room after keeping her swipe card which she was required to hand over after resigning from the organisation.
A family member discovered the drugs at her home and notified the hospital and police.
In the Hamilton District Court for her sentencing yesterday, Millar's lawyer, Mike Curran, said although she was currently suspended by the Nursing Council, he expected her to be re-employed at a later stage.
"She has had an indication from the nursing council that she will only be admitted if they deem her to be a suitable person and that is obviously something in the future that she can work towards but certainly she won't be doing that in the near future.
"Clearly she is a woman of some skill and ability and within the fullness of time she will be re-employed because her skills are too valuable to lose."
Millar at the time was suffering an unmanageable addiction which eventually led to the offending, he said.
Judge Philip Connell said the breach of trust against her co-workers was the most aggravating feature.
"In a case like this where Ms Millar works with other colleagues in the hospital they have to trust each other. For me one of the aggravating features of this is the way that she has let them down and for me, is probably the worst aspect of this offending."
He accepted her remorse and the fact she has not offended before.
He sentenced her to 12 months' supervision and 220 hours' community work on charges of burglary and theft.
She also has to pay reparation of $2,500 at $25 per week after an initial payment of $2,500.