Managing diabetes mellitus in cats: What makes it work? (Sponsored by Intervet Schering-Plough Animal Health)
Jun 01, 2008
While sometimes thought of as a disease entity, diabetes mellitus is a heterogeneous group of disorders in which insulin production is reduced or tissue cells are resistant to the effects of insulin, resulting in impaired glucose homeostasis.
In cats, the categorization of diabetes is not as clear. Generally, diabetes is a disorder of older, often overweight cats that are not prone to ketogenesis, more similar in signalment to type II diabetes in people. However, obese cats appear to have a defect in insulin secretion along with lower tissue sensitivity to insulin.1,2 Weight loss of even 10% to 15% results in improved tissue sensitivity, but, often by the time of diagnosis, these cats require treatment with insulin. Cats may also develop diabetes secondary to primary pancreatic disease, endocrinopathies (e.g., acromegaly, hyperadrenocorticism), or drug therapy (e.g., glucocorticoids, progestins). Risk factors for feline diabetes include weighing greater than 7 kg (15.4 lbs), not being physically active, or being over 9 years old, a neutered male, or a Burmese.1,3Complications of unregulated diabetes mellitus
In short, diabetes mellitus results in cell starvation in the presence of hyperglycemia. While cell starvation results in polyphagia with concurrent weight loss, hyperglycemia results in polyuria and compensatory polydipsia due to glucose spilling into the urine and osmotically drawing water with it.
A recent study investigated associations among clinical signs, serum biochemical markers, and urinalysis results and found that, "Many of the cats with urinary tract infections had no clinical signs of lower urinary tract disease or changes in their laboratory values indicative of infection. Therefore, a urinalysis alone should not be used to exclude urinary tract infections in these cats."7 I recommend a urine culture for this purpose. An interesting report of pulmonary changes (such as congestion, edema, pneumonia, fibrosis, mineralization, and neoplasia) in diabetic cats without clinical signs of respiratory disease also shows the need for greater vigilance in monitoring the respiratory system.8