It was almost compulsory in Australia to have a DUI (spent). It is an opportunity to show maturity and growth. "Yes, I made a foolish error when I was young but I have since learned the error of my ways and ensured that it never happened again. etc".
My husband has a spent (well and truly spent - 30 years ago) DUI in Australia. Didn't stop him getting an airline job in Australia and now in the UK.
I wouldn't lie if you have one. Things are worse for you if you do. However, I doubt it'll be an Airside pass stopper. It also shouldn't stop you from operating into the US etc.