The chief signs of diabetes are increased drinking, increased urination, and weight loss. Insulin is needed for transporting basic food substances, particularly sugar or glucose, into body cells, says Henson, a resident in internal medicine and a feline-diabetes researcher at the University of Minnesota. The body uses sugar for energy, growth, and repair. Without enough insulin, glucose accumulates in the bloodstream. Because it cannot move into the tissues where its presence is required, it is lost in urine.
Body water is lost in urine, too.
Consequently diabetics produce a large volume of urine. Cats urinate more frequently, or they urinate outside the litterbox. The high urine output also increases thirst. Although blood-glucose levels are excessively high in diabetic cats, their tissues are starving for energy because glucose cannot get into their cells. As a result, diabetic cats usually lose weight.