there is a risk with pd of injuries such as shin splints and plantar faciitis due to tightness in the calf muscles. toes. etc
extra care needed with stretching, good shoes etc. if pain starts don't ignore it - it will get worse unless the underlying problem is dealt with.
i have to add, and i'm very sorry to say this but i feel i must - a marathon is not a good idea.
but best of luck and i very much hope i'm totally wrong and you succeed with the marathon.