Diabetic cats are quite different because dietary formulation may facilitate reversal of the diabetes.^13,14 Low-carbohydrate and high-protein diets are recommended (e.g. Purina Veterinary Diets DM—Nestlé Purina, Prescription Diet m/d—Hill's), although other medical problems such as kidney disease may limit dietary manipulations. As cats can be finicky, finding a well-tolerated and palatable balanced diet is the most important consideration. Canned food tends to be lower in carbohydrates than dry food, but dry kitten chow is an acceptable option if a cat declines one of the therapeutic diabetic diets. It isn't necessary to meal-feed cats receiving PZI or glargine, as both are well-suited to their natural tendency to eat small amounts frequently. Foods high in simple sugars, such as semi-moist diets and treats, should be avoided. Obesity is a well-recognized cause of insulin resistance in cats, and gradual weight loss may improve glycemic control and encourage endogenous insulin production.

Oral hypoglycemic therapy

Dogs with diabetes mellitus are always insulin-dependent, so the oral hypoglycemic drugs are never appropriate. Although some cats respond to glipizide (thought to enhance endogenous insulin production), most are not adequately controlled, and the prolonged hyperglycemia may contribute to glucose toxicity and reduce the chance of eventual diabetic remission.¹⁵ I would only prescribe glipizide if a client refused to administer insulin, and I would combine it with appropriate dietary modification and weight loss (if necessary). Acarbose (an enzyme inhibitor that impairs intestinal glucose absorption) may facilitate glycemic control in cats fed a low-carbohydrate diet.¹⁶ However, the effect seems modest, at best, and it cannot be used in place of insulin.

Most dogs and cats with diabetes are successfully managed and continue to be a source of joy and comfort to their families. Effective client communication is essential, as pet owners need to feel supported by the veterinary team, particularly at the time of diagnosis. It is important to stress the benefits of regular rechecks and to explain that dose adjustments are a routine part of diabetic care. Encouraging owners to check glucose concentrations at home can be empowering, and many Web sites offer guidance and support (e.g. http://petdiabetes.org/, http://caninediabetes.org/, http://felinediabetes.com/). Reinforce to owners that diabetes mellitus is a treatable disease, and most patients enjoy an excellent quality of life.

Audrey K. Cook, BVM&S, MRCVS, DACVIM (internal medicine), ECVIM-CA
Department of Small Animal Clinical Sciences
College of Veterinary Medicine and Biomedical Sciences
Texas A&M University
College Station, TX 77843

REFERENCES

1. Nelson RW. Diabetes mellitus. In: Ettinger SJ, Feldman EC, eds. Textbook of veterinary internal medicine. 6th ed. St. Louis, Mo: Elsevier Saunders, 2005;1563-1591.

2. Rand JS, Marshall RD. Diabetes mellitus in cats. Vet Clin North Am Small Anim Pract 2005;35(1):211-224.

3. Peterson ME, Melian C, Nichols R. Measurement of serum concentrations of free thyroxine, total thyroxine, and total triiodothyronine in cats with hyperthyroidism and cats with nonthyroidal disease. J Am Vet Med Assoc 2001;218(4):529-536.

4. Graham P, Nash AS, McKellar QA. Pharmacokinetics of porcine insulin zinc suspension in diabetic dogs. J Small Anim Pract 1997;38(10):434-438.

5. Horn B, Mitten RW. Evaluation of an insulin zinc suspension for control of naturally occurring diabetes mellitus in dogs. Aust Vet J 2000;78(12):831-834.

6. Melendez L, Lorenz M. Canine diabetes mellitus, in Proceedings. Western Vet Conf 2002.