scab. 1  An incrustation over a sore, wound, vesicle, or pustule, formed during healing. 2  The mange, especially when it appears on sheep. 3  Any of several different diseases of potatoes producing pits and other damage on their surface, caused by streptomyces bacteria (but formerly believed to be caused by a fungus).
Diabetes complications from fungus infections in the toenails and fingernails can lead to amputations of the entire limbs. To understand how serious fungal toenails can be to a diabetic, you must first understand how diabetes affects the body.
Neuropathy in your feet or legs indicates that any infection you get in your feet could flare up and result in an incurable infection that would require amputation. This means you need to treat any foot infection, including fungal infections like Athlete's Foot, as an emergency requiring a trip to the doctor.