Dry gangrene is more common in people with blood vessel disease, diabetes, and autoimmune diseases. Dry gangrene usually affects the hands and feet. It develops when blood flow to the affected area is impaired, usually as a result of poor circulation. In this type, the tissue dries up and may be brown to purplish-blue to black in color and often falls off. Unlike other types of gangrene, infection is typically not present in dry gangrene. However, dry gangrene can lead to wet gangrene if it becomes infected.