A high K_m indicates a high affinity of the enzyme for the substrate and results in a higher reaction velocity.

A low K_m indicates a low affinity of the enzyme for the substrate and results in a higher reaction velocity.

A high K_m indicates a low affinity of the enzyme for the substrate and requires a higher substrate concentration to reach half of the maximum reaction velocity (V_max).

K_m has no relationship with enzyme-substrate affinity or reaction velocity.