Gangrene is a type of necrosis caused by a critically insufficient blood supply. This potentially life-threatening condition may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood supply to the affected tissues, which results in cell death. Diabetes and long-term smoking increase the risk of gangrene. Gangrene is not a communicable disease; it does not spread from person to person, though the infection associated to some forms can. The types of gangrene differ in symptoms, and include dry gangrene, wet gangrene, gas gangrene, internal gangrene, and necrotizing fasciitis. Surgical removal of gangrenous tissue and antibiotics are the mainstays of treatment for gangrene. After the gangrene is treated, the underlying cause is addressed. This includes lifestyle modification such as smoking cessation, better control of diabetes, revascularization or, rarely, medical therapy to stop vascular spasm or the production of cold-induced vascular obstruction by cold-precipitated cryoglobulins.