Failing Hearts in Diabetic Cats

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.

COMMENTARY: The finding of increased incidence of heart disease in cats with diabetes is important and worthy of further investigation. As acknowledged by the authors, weaknesses of the study include the retrospective nature, small study group, and absence of blood pressure measurement to assess for hypertension in these cats. In addition, not all cats were tested for hyperthyroidism at the time of diagnosis. The selection of patients diagnosed in a general practice setting highlights a common weakness in much of the veterinary literature-studies are often based on patients seen in a tertiary referral setting, which unintentionally selects for patients whose owners can pursue specialty care, either due to regional availability or financial capability of the owners. In addition, limiting the scope of the study to a primary care facility potentially selects for patients with fewer complications of diabetes and thus might not reflect the true incidence of heart failure.

Heart failure is common in diabetic cats: Findings from a retrospective case-controlled study in first-opinion practice. Little CJL, Gettinby G. J SMALL ANIM PRACT 49:17-25, 2008.