Hello....... as it is a complicated case i cannot advise you accurately without knowing his vitals, lab results, general condition etc...... but if the wound is infected and discharging pus then take him to the diabetologist
he will keep him on insulin
and do the culture and sensitivity of pus, basing on the results we can use the antibiotics to which the organism is sensitive and can stop the worsening of wound. if there is no infection then u can use ointments
like Helace (which contains the platelet derived growth factor) for good closure of wound but it should not be used if there is infection.