diabetes (n.) Look up diabetes at Dictionary.com
1560s, from medical Latin diabetes, from late Greek diabetes "excessive discharge of urine" (so named by Aretaeus the Cappadocian, physician of Alexandria, 2c.), literally "a passer-through, siphon," from diabainein "to pass through," from dia- "through" (see dia-) + bainein "to go, walk, step," from PIE root *gwā- "to go, to come" (see come).

An old common native name for it was pissing evil. In classical Greek, diabainein meant "to stand or walk with the legs apart," and diabetes meant "a drafting compass," from the position of the legs.