Diabetes is often thought to be an internal cause of pruritus, but in fact most patients with diabetes do not experience pruritus. If this does occur, the first thing to look for is the presence of primary lesions or the presence of other causes. The more common causes of pruritus are liver diseases such as obstructive hepatitis, and the pruritus caused by these systemic diseases is also usually generalized, usually limited to the palms of the hands in a relatively small number of cases.