Diabetes mellitus is a fairly common endocrine disorder in cats and incidence has recently increased. Very little is known regarding the prognosis or cause of death in cats with diabetes. In humans with diabetes, death is frequently related to cardiovascular disease. These authors attempted to ascertain the prognosis and cause of death in cats in which diabetes was diagnosed at a general practice compared with nondiabetic patients of similar signalment during a 6-year period (1999 to 2005). They found that 6 of 14 cats with diabetes died of heart failure within 5 weeks to 30 months of diagnosis. Treatments for these cats included insulin (usually Lente), diet, and/or oral hypoglycemic medications. In contrast, 2 of 57 control cats died of heart failure. Cats with diabetes were 10 times more likely to have heart disease and 3.4 times more likely to die than healthy controls. The type of heart disease seen in the diabetic cats varied.