A diuretic is anything that promotes the formation of urine by the kidney. Diuresis may be due to a huge number of causes including metabolic conditions such as diabetes mellitus (in which the increased glucose level in the blood causes water to be lost in the urine); substances in food and drink (such as coffee, tea, and alcoholic beverages); and specific diuretic drugs. All diuretic drugs – which are usually called, more simply, diuretics – cause loss of water but they do so by diverse means, including: Inhibiting the kidney’s ability to reabsorb sodium, thus enhancing the loss of sodium in the urine. And when sodium is lost in the urine, water goes with it. This type of diuretic is called a high-ceiling diuretic or a loop diuretic, enhancing the excretion of both sodium and chloride in the urine so that water is excreted with them. This is how the thiazide diuretics work. The thiazides result in potassium loss and potassium supplementation is usually required. Some diuretics work by still other mechanisms. And some diuretics have other effects and uses such as in treating hypertension.