D-Mannose is a simple sugar that occurs naturally in some plants, including cranberries. Although small amounts of D-Mannose are metabolized by the human body, much of it is rapidly excreted in the urine. In the bladder, D-Mannose can adhere to bacterial lectins, preventing them from sticking to the lining of the bladder. Bacteria can then be flushed away during urination, thereby precluding the formation of colonies within the urinary tract. Because insubstantial amounts of D-Mannose are used by the body, it does not interfere with blood sugar regulation.