welcome to hcm
thanks for the query
the non healing of the wound is due to poor control of blood sugar level
is poorly controlled then it affects the arteries which cause in non healing.
so first of all control his blood sugar level by proper medication and insulin
if all higher antibiotics fail then you can go for hyperbaric oxygen
it showed good result in many patients
other options are graft placement,growth factor therapy ang matrix metall-oproteinase therapy.
but these options can be available in good tertiary care centers.
maintain proper nutrition.
wish him a good recovery.