Although they have a common name, [[diabetes mellitus]] and [[diabetes insipidus]] are two entirely separate conditions with unrelated mechanisms. Both cause large amounts of [[urine]] to be produced ([[polyuria]]), and the term "[[diabetes]]" is derived from the Greek word meaning siphon. However, diabetes insipidus is either a problem with the production of [[antidiuretic hormone]] ([[central diabetes insipidus]]) or kidney's response to antidiuretic hormone (nephrogenic diabetes insipidus), whereas [[diabetes mellitus]] causes [[polyuria]] via a process called osmotic [[diuresis]], due to the high blood sugar leaking into the urine and taking excess water along with it.