Completing med school pre-reqs after undergrad degree?

I'm currently in college and am pretty sure I want to pursue an engineering degree. However, a nagging part of me still thinks that I might want to go to medical school. There isn't really any way for me to complete all the requisites for medical school (specifically the life science and o-chem ones) while I'm in college. So I was thinking that once I graduate, if at some point I ever decide I want to go to medical school I would just go to the local community college to pick up whatever classes I need to fill the requirements. Do medical schools care if you do this? Is it frowned upon in the admissions process to get a degree from a major university and then go to a community college for those classes? Theoretically I could take care of them in summer school here but it's kind of expensive so I would rather avoid that.