This largely depends - DNR doesn't mean do not treat. I may have a pt who is a DNR who is perfectly alert and oriented, mostly independent and in with cellulitis. If I walk into the room and they are unresponsive I'm calling a MET call - maybe they had an MI or stroke and need treatment ASAP.
If I have a pt. that is deteriorating over the course of week, and eventually has poor sats, bad vitals/labs but has expressed to me they want everything done short of compressions/being intubated, I'm calling a MET call.
If I have a pt that has been poor, family knows they are poor, pt has no plans to ever recover etc. then I would treat whatever symptoms they have, oxygen, lasix, etc.
I always try to evaluate which patients want comfort care/hospice, vs treatment but not compressions, etc. I think so many people are hesitant to sign a DNR because they think we will no longer treat them. And unfortunately I've been in many arguments with MD's because they think the patients DNR means they are comfort care, when the pt. has clearly expressed that they want treatment. I may not agree with it, nor the MD, given the patient's condition, but its not really our decision to make.