Gangrene, a condition which occurs when bodily tissue dies, can set in at different rates depending on the type. MedicineNet defines two main types of gangrene: dry and wet. Dry gangrene can develop over the course of months, while wet can develop quickly, sometimes in a few hours.
MedicineNet states that dry gangrene is caused by gradual arterial blockage, as is often seen in diabetics. This kind of gangrene has a slow progression of days to months. Wet gangrene, the result of injury and rapidly cut-off blood supply, nearly always involves infection and can develop over a few hours or days. The resulting sepsis, or blood infection, can become fatal if not treated quickly, warns WebMD.