Some medical schools require a certain minimum GPA to apply and other schools do not. In reality however, this minimum cutoff GPA is absolutely irrelevant. The GPA needed to be a competitive applicant at a particular school and the GPA required to apply to that school are never even remotely similar.
For example, the University of Utah School of Medicine has a minimum GPA et at 3.0. This means that they will not consider any applicants with a GPA under 3.0. However, if you apply to this school with a 3.0 GPA, you have about a zero percent chance at gaining admissions at this school.
For most medical schools, you will need at least a 3.5 GPA to be just somewhat competitive. In 2012, the mean science and overall GPA of matriculants were 3.63 and 3.75 respectively. The mean and overall GPA of applicants was 3.44 and 3.66 respectively.