How to Feed Cats with Diabetes

Diet plays a key role in the successful management of the diabetic cat. Because cats are obligate carnivores (1-3), diabetic cats are relatively carbohydrate intolerant and respond best to a low carbohydrate diet. This differs from dogs, which are omnivores and are quite tolerant of a moderate to high carbohydrate meal, even when diabetic (4,5).

Evolutionary events shaped the cat’s core metabolism such that their systems are uniquely set up to metabolize a diet which is high in moisture, high in protein, and very low in carbohydrates. Because this is the diet they have relied upon for tens of thousands of years, they do not have the ability to process carbohydrates very efficiently and show relative carbohydrate intolerance (1-3). This becomes extremely important when selecting a diet for cats with diabetes.

Postprandial Glycemia in Man, Dogs, and Cats
As a result of these differences, plasma glucose clearance rates are longer in cats compared to dogs or humans after feeding a moderate to high carbohydrate meal — in other words, even normal cats have much more prolonged postprandial period of hyperglycemia than might be expected. In healthy humans and dogs, postprandial hyperglycemia normally persists for 2 to 6 hours (4,6).

In contrast, recent studies of healthy cats found that both serum glucose and insulin concentrations remained significantly increased for a median time of 12 hours following ingestion of a moderate carbohydrate meal (25% of calories), and that both glucose and insulin concentrations remained above baseline values for 24 hours in approximately 20% of the cats (7,8). Most feline diets contain even higher amounts of carbohydrate (greater than 25%) and, therefore, would be expected to result in more severe postprandial hyperglycemia and a longer time to return to baseline.

Management Goals of Feline Diabetes
In cats with diabetes, a primary goal of therapy is to feed a diet that will lessen postprandial hyperglycemia, reduce marked fluctuations of blood glucose concentrations, minimize the demand on beta cells to produce insulin, and improve insulin sensitivity (9-11). By doing this, we decrease the effect of “glucose toxicity” and hopefully allow the pancreatic islet cell to partially recover. In about half of newly diagnosed diabetic cats, this will lead to remission of the diabetic state (12-14).

A secondary goal of therapy is to provide a diet that will help normalize body weight and maintain and/or restore lost muscle mass (15,16). I'll be covering the reason why higher protein diets are also important for diabetes in my post next week.

Recommendations for Diabetic Cats: Low Dietary Carbohydrates:
It is well accepted dogma, at least by most practicing veterinarians who specialize in feline medicine, that feeding a low-carbohydrate diet is the mainstay in the treatment of diabetes mellitus, especially if remission of the diabetic state is the goal. In accord with that, there is strong clinical and research evidence that a diet containing very low concentrations of carbohydrate (e.g., carbohydrates less than 12% of calories) is the most effective means for achieving our nutritional goals for cats with diabetes (5,9,17-19).

Feeding a low carbohydrate diet will improve insulin sensitivity, help stabilize glucose metabolism, and can reduce or eliminate the need for exogenous insulin in these cats (5,20,13,14).  The likely mechanism for these observations is relatively simple —decreasing dietary carbohydrate load reduces the postprandial blood glucose elevation, which in cats is prolonged, sometimes lasting for over 12 hours (7,8).

In some diabetic cats, decreasing carbohydrate content to a level significantly less than 12% of the daily calories may help increase their rate of remission. In accord with that, the highest remission rates (greater than 80%) have been reported feeding diets with approximately 6% of energy from carbohydrate (21).

If a change in feeding to a low-carbohydrate diet is made in a diabetic cat already stabilized on insulin, it is extremely important to realize that this will result in a lowered daily insulin dosage — often significantly (9.20). If not closely monitored—ideally with home glucose testing— severe hypoglycemia can develop in these cats because they become more sensitive to insulin after the diet composition is changed.

Therefore, when changing from a higher-carbohydrate to a low-carbohydrate diet, we recommend initially reducing the insulin dose by 30% to 50% to help avoid hypoglycemia. If the diabetic cat goes into remission (no more insulin needed to maintain euglycemia), we recommend maintaining the low-carbohydrate diet for life to help prevent relapse of the diabetic state.

References:

1. MacDonald ML, Rogers QR, Morris JG. Nutrition of the domestic cat, a mammalian carnivore. Annu Rev Nutr 1984;4:521-562. 
2. Zoran DL. The carnivore connection to nutrition in cats. J Am Vet Med Assoc 2002;221:1559-1567. 
3. Eisert R. Hypercarnivory and the brain: protein requirements of cats reconsidered. J Comp Physiol B 2011;181:1-17. 
4. Elliott KF, Rand JS, Fleeman LM, et al. A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs. Res Vet Sci 2011;93. 
5. Rucinsky R, Cook A, Haley S, et al. AAHA diabetes management guidelines. J Am Anim Hosp Assoc 2010;46:215-224. 
6. American Diabetes Association. Postprandial blood glucose. Diabetes Care 2001;24:775-778. 
7. Farrow H, Rand JS, Morton JM, et al. Postprandial glycemia in cats fed a moderate carbohydrate meal persists for a median of 12 hours -- female cats have higher peak glucose concentrations. J Feline Med Surg 2012;14:706-715. 
8. Farrow HA, Rand JS, Morton JM, et al. Effect of dietary carbohydrate, fat, and protein on postprandial glycemia and energy intake in cats. J Vet Intern Med 2013;27:1121-1135. 
9. Rand JS. Feline diabetes mellitus In: Mooney CT, Peterson ME, eds. BSAVA Manual of Canine and Feline Endocrinology. Fourth ed. Quedgeley, Gloucester: British Small Animal Veterinary Association, 2012;133-147.
10. Rand JS. Pathogenesis of feline diabetes. Vet Clin North Am Small Anim Pract 2013;43:221-231. 
11. Zini E, Osto M, Franchini M, et al. Hyperglycaemia but not hyperlipidaemia causes beta cell dysfunction and beta cell loss in the domestic cat. Diabetologia 2009;52:336-346. 
12.  Zini E, Hafner M, Osto M, et al. Predictors of clinical remission in cats with diabetes mellitus. J Vet Intern Med 2010;24:1314-1321. 
13. Reusch CE, Hafner M, Tschuor F, et al. Diabetes remission in cats: a review. Schweiz Arch Tierheilkd 2011;153:495-500. 
14. Gottlieb S, Rand JS. Remission in cats: including predictors and risk factors. Vet Clin North Am Small Anim Pract 2013;43:245-249. 
15. Nguyen P, Leray V, Dumon H, et al. High protein intake affects lean body mass but not energy expenditure in nonobese neutered cats. J Nutr 2004;134:2084S-2086S. 
16. Keller U. Dietary proteins in obesity and in diabetes. Int J Vitam Nutr Res 2011;81:125-133. 
17. Baral RM, Little SE. Endocrine pancreatic disorders In: Little SE, ed. The Cat: Clinical Medicine and Management. St. Louis: Elsevier Saunders, 2012;547-571.
18. Bennett N, Greco DS, Peterson ME, et al. Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus. J Feline Med Surg 2006;8:73-84. 
19. Boari A, Aste G, Rocconi F, et al. Glargine insulin and high-protein-low-carbohydrate diet in cats with diabetes mellitus. Vet Res Commun 2008;32 Suppl 1:S243-245. 
20. Zoran DL, Rand JS. The role of diet in the prevention and management of feline diabetes. Vet Clin North Am Small Anim Pract 2013;43:233-243. 
21. Roomp K, Rand J. Evaluation of detemir in diabetic cats managed with a protocol for intensive blood glucose control. J Feline Med Surg 2012;14:566-572.