Yes, and it comes from the underlying circulation problem rather than from the wound on its own. The possible complications of peripheral artery disease of the legs include open sores (ischemic ulcers on the lower legs), tissue death (gangrene), and the affected leg or foot may need to be amputated. The ulcer and the gangrene are on the same list because they come from the same cause.
That cause is simple. Narrowed arteries prevent a healthy supply of blood from flowing to the legs. This means that the tissues in your legs do not get enough nutrients and oxygen. The lack of nutrients causes cells to die, damaging the tissue. Gangrene is that process taken further.
Severe disease has a look, too. When peripheral artery disease is more severe, signs include painful, non-bleeding sores on the feet or toes (most often black) that are slow to heal, and paleness of the skin or blue color in the toes or foot (cyanosis). Ischemic ulcers can be dark red, yellow, gray, or black sores.
The part worth holding on to is that the main factor is treatable. To treat an ischemic ulcer, blood flow to your legs needs to be restored. You may need to take medicine. In some cases, you may need surgery. Gangrene being a possible complication is not a forecast about you. It is the reason the blood-flow question carries so much weight with these wounds.
Color changes are their own reason to call, separate from any sign of infection. Contact your provider if your foot ulcer is very white, blue, or black. Also contact your provider if a leg or foot becomes cool to the touch, pale, blue, or numb.
One honest limit, and it matters here more than anywhere. There’s no way to tell at home whether tissue has died, and this article can’t tell you how likely it is or how long it takes. Black or blue tissue on a foot is a reason to be seen — not a diagnosis to reach on your own.