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. Diabetes is one of the most common hormonal imbalances in cats. Because obesity by itself can cause insulin resistance, overweight cats are more likely to be afflicted with diabetes.