Your GPA's won't be the issue. Your science/BCPM GPA would be a bit more important. However, the issue is why you want to go into medicine after completing a Ph.D. in engineering. Now there are a couple of schools that would be fine with it (Carle, Texas A&M, soon Arizona State), but how you learn in medical school is different than graduate school leading to a Ph.D. You also must show you are fine starting at the bottom of the totem pole as a lowly med school grunt. 🙂