These are caused in response to repeated pressure or friction from rubbing and can occur any where on the body, usually the hands or feet. On the feet they are frequently caused by preasure frome ill fitting shoes, the bodies reaction to pressure and friction is to produce a thickened area of skin ( callus) over a period of time to protect that area, too greater friction produces a blister.
These are a particular type of callus forming on hairless smooth skin surfaces on the upper side of toes or fingers and are caused by a circular rubbing motion forming a raised circular patch of hard skin with a conical centre. This conical centre with the apex pointing inwards, may cause deep skin damage, pain and sometimes ulceration.
Choosing well fitting shoes is the best defense.
Corns and hard skin are the most common conditions our podiatrist has to treat, using either an abrasive or "dig out" the hard skin mass using a scalpel.
Because of the circulatory problems associated with diabetes and loss of sensation there is an increases risk of ulceration and other potentially serious consequences so that much greater care and vigilance is needed and foot care best left to the professional.