The math you need to be able to qualitatively understand medicine enough to be a decent physician is very minimal. Basics of calculus, geometry, algebra, and a good understanding of log scales and relationships is really it. Just for basic biochem, pharmacology, and acid-base balance really. No integrations, derivations, or differential equations. 😉 AND, most med schools know that hard math is a weak point of their students, so there are review classes as you go along, tutoring programs, and profs at most places tend not to get frustrated if you're seeking help and really trying to "get it."
That's certainly how it is where I am, and from what students in at other school's tell me, it's true too.
I used to worry about this issue, but honestly, they give you enough chances to learn the basic math relationships; you don't have to have prereqs upon prereqs to do well in the math-heavy units of med school. As long as you get the prereqs for most schools done, anyway.