How long can a 22 year old male reasonably have type 1 diabetes before going into dke?

A long time: Patients that regularly take their insulin rarely if ever have DKA. I have patients who have had type 1 diabetes for 15-20 Years without ever having DKA. In a well controlled type 1 things that can cause dka are acute illness, insulin pump issue, forgetting to take insulin. If you havent had DKA thats great! Good work! It sounds like you are doing well.