 Non-diabetic subjects will be requested to fast overnight and to avoid changes in non-steroidal anti-inflammatory agents or medications that block the renin-angiotensin system. Subjects with diabetes will be asked to eat a light breakfast the morning of the study visit. Subjects will be asked to maintain adequate oral hydration and to ingest two to three glasses of non-caffeinated beverages prior to arrival to facilitate the collection of a baseline urine collection and an additional two to five glasses upon arrival at the CTRC. 