The kidneys are bean-shaped organs, approximately the size of a fist. They remove wastes and extra water from the blood to the urine. The waste and extra water from the kidneys becomes urine and goes through tubes called ureters to the bladder, where it is released when a person urinates. The kidney also measures chemicals such as protein, sodium and potassium in the blood. This measuring is done through tiny filtering units inside the kidneys called nephrons and through the glomeruli which are blood-filtering units that are surrounded by nephrons. It is around the glomeruli that most of the diabetic damage to the kidneys occurs. If the waste is not removed by the kidneys, then the waste accumulates in the blood and damages the body.