Dear sir I understand your concern.i am a Diabetologist my suggestion for you....usually wound will heal little slowly in diabetes.for better wound healing sufficient offloading of the foot is very important.its very important to get your vascular supply checked,for that you can undergo a test called vascular Doppler .next in long standing non healing ulcer it s better to take X-ray and check for bone infection also.in my opinion you may need consultation with podiatric surgeon also.the latest treatment modalities like vaccum assisted closure therapy and hyper bardic oxygen therapy will give better results......for any clarification you can get back to me regards....