D-mannose is a naturally occurring simple sugar that your body utilizes to help cleanse the urinary tract and maintain a healthy bladder lining. It's metabolized only in small amounts, with excess amounts rapidly excreted in urine, so it won't interfere with healthy blood sugar regulation. Clinical studies have demonstrated that, when taken regularly, D-mannose promotes normal urinary tract function by cleansing and maintaining the health of the bladder lining.