An update in the epidemiology and nutritional management of DM in cats 

Diabetes mellitus is a complicated condition caused by either an absolute or relative lack of insulin hormone. It is treated with a combination of diet, insulin and blood glucose monitoring. Only diet will be considered in this article.

Epidemiology

Diabetes mellitus (DM) is a common disease of cats. The prevalence reported varies, but the most recent and extensive study in England shows 0.58%  of cats seen in primary care practice [1]. Of these, 44.7% were known existing cases, the remaining were discovered incidentally, thus probably an accurate reflection of true epidemiology within the cat population. Other studies looking at cohorts of insured cats report prevalence ranging from 0.21% in Sweden [2], 0.74% in Australia [3] to 1.24% in USA [4]. However, with only a small percentage of cats being insured, their diagnosis, treatment and management is unlikely to be representative of the wider feline population.

DM in cats most closely resembles human type 2 DM: a combination of insulin resistance and decreased pancreatic b cell function. Environmental factors contribute to risk- increasing age with a peak in diagnoses at 14 years [1], physical inactivity and obesity [5] [6]. Obesity is a huge risk factor in human type 2 DM- mediated through chronic adipose inflammation, leptin and insulin resistance [7]. It is not fully understood if exactly the same mechanism exists in cats, but risk of DM progressively increases with increasing bodyweight [1] as do circulating insulin and leptin concentrations [8]. Preventing obesity in young cats and achieving weight loss in older overweight cats are key factors in reducing the risk of diabetes.

There is likely a genetic component to DM, as the rate appears higher in Burmese, Tonkinese (a breed derived from Burmese) and Norwegian Forest cats, and lower in Persians compared to cross breeds. Interestingly, American Burmese are not reported at higher risk- they are genetically distinct from other Burmese worldwide [1, 9]. Historically male cats were reported to be at higher risk, but the English study reports no sex predilection after other risk factors were accounted for [1] [9].

In cats there are other known causes of DM: Hypersomatotropism (HS, acromegaly) is estimated to cause 25% of UK feline DM cases, but interestingly, 76% of these cases did not display typical acromegalic signs [10]. The increasing bodyweight seen in acromegalic cats will contribute to the association between body weight and DM.  Hyperadrenocorticism, usually presenting with uncontrolled DM and dermatological signs [11], pancreatic disease [12] and diabetogenic drug administration [13] are other recognised, but rarer causes [14]. Cats with pituitary-dependant hyperadrenocorticism experience significant improvement in quality of life when treated with Trilostane [11]. Cats with HS associated DM should have HS treatment options discussed with owners- these vary in efficacy and availability and include surgical and medical options. Radiotherapy, surgical pituitary removal, surgical cryoablation of pituitary gland, pasireotide (somatostatin analogue) and cabergoline (dopamine agonism) have all been trialled with varying results [15].

Management considerations

DM is usually a treatable condition, but it is not simple to manage, and requires dedication and commitment from owners. The goal is now achieving diabetic remission rather than just controlling clinical signs. A cat in diabetic remission is normoglycaemic with no need for insulin. Another the key factor in successful management is communication between veterinarian and owner. A recent survey of owners of DM cats found that this to be significantly lacking, with 76% of respondents citing the internet as their primary source of information [16].

Role of diet

Diet plays a significant part in management. If the cat is overweight this should be normalised to help reduce insulin resistance. In some cases, this can be enough to achieve diabetic remission [17]. Successful weight loss strategies have been discussed in previous articles (LINK) but generally the nutritional profile should be: fat< 4g/100kcal, carbohydrates (CHO) <3g/100kcal and protein >10g/100kcal [18]. This low level of CHO is easier to achieve in wet formulations as it impacts the extrusion in dry food manufacture. Dietary management should be implemented soon after diagnosis when the cat is eating well, to optimise chances of remission.

Aside from normalisation of weight and lean muscle mass, the main goals of dietary therapy are:

• Reduce postprandial blood glucose to facilitate reversal of beta cell toxicity and recovery of insulin secretory capacity.
• Reduce fluctuation of blood glucose after eating and thus the potential for marked hyperglycaemia or clinical hypoglycaemia.

When considering the diabetic cat, there is strong clinical and research evidence that a diet containing protein as the major source of ME (>40% or >10g/100kcal) and low levels of CHO (<15% ME or <3g/100kcal) is the most effective way to meet all these goals: normalise body weight, maintain/ regain muscle mass, reduce post-prandial hyperglycaemia and minimise blood glucose fluctuations [17, 19, 20]. Once in diabetic remission, the cat should continue on the special diet; they will continue to have reduced glucose tolerance, and around 1 in 4 cats will revert from remission to overt diabetes even whilst maintaining the prescribed diet [21].

In addition to the amount of CHO, the type of CHO is also important. It should be a complex CHO with low glycaemic index. The feasible sources vary, depending on whether the diet is dry or wet, as manufacturing process can be affected. Novel CHO such as lentil and cassava flour have shown no post prandial glucose increase and minimal insulin response [22].

There are currently no firm recommendations in feeding patterns for DM cats. Cats tend to prefer to graze on small amounts of food throughout the day, but it is helpful if a measured amount of food can be given at the time of insulin injection. The owner can then be sure the cat is eating appropriately at least twice a day. There is no published data on the effect of different feeding patterns and frequencies on post prandial blood glucose concentrations.

Whilst it is good to implement the diabetic diet as soon as possible, it is important it is not offered until the sick diabetic cat is stabilised, as food aversion may occur. Feeding recommendations become slightly more complicated when there are concurrent diseases. When the probability of remission is low (acromegaly, end-stage pancreatitis, chronic kidney disease), the goal should be to minimise hyperglycaemia and hypoglycaemia, whilst treating the other condition with appropriate diet. For example, it is not appropriate to feed a cat in stage 3 renal disease a high protein diabetic diet, feeding for renal disease should be the priority.

Royal Canin diabetic dry diet for cats contains 11.9g protein/ 100kcal, 3.1g fat/ 100kcal and 4.9g CHO/ 100kcal. The wet version contains 11.5g protein/ 100kcal, 4.1g fat/ 100kcal and 1.5g CHO/ 100kcal. This makes the diets idea for achieving the dietary goals for DM cats.

Conclusion:

Nutrition is an integral part of the care for a cat with diabetes, despite this, over one third (39%) of cats with diagnosed diabetes are NOT fed a ‘diabetic’ diet [16]. Without appropriate diet, diabetic remission is not a realistic goal.

References

1. O’Neill, D.G., et al., Epidemiology of Diabetes Mellitus among 193,435 Cats Attending Primary-Care Veterinary Practices in England. J Vet Intern Med, 2016. 30(4): p. 964-72.
2. Sallander, M., J. Eliasson, and A. Hedhammar, Prevalence and risk factors for the development of diabetes mellitus in Swedish cats. Acta Vet Scand, 2012. 54(1): p. 61.
3. Lederer, R., et al., Frequency of feline diabetes mellitus and breed predisposition in domestic cats in Australia. Vet J, 2009. 179(2): p. 254-8.
4. Prahl, A., et al., Time trends and risk factors for diabetes mellitus in cats presented to veterinary teaching hospitals. J Feline Med Surg, 2007. 9(5): p. 351-8.
5. Öhlund, M., M. Palmgren, and B.S. Holst, Overweight in adult cats: a cross-sectional study. Acta Vet Scand, 2018. 60(1): p. 5.
6. Scarlett, J.M. and S. Donoghue, Associations between body condition and disease in cats. J Am Vet Med Assoc, 1998. 212(11): p. 1725-31.
7. Lee, B.C. and J. Lee, Cellular and molecular players in adipose tissue inflammation in the development of obesity-induced insulin resistance. Biochim Biophys Acta, 2014. 1842(3): p. 446-62.
8. Williams, M.C., et al., Association of circulating adipokine concentrations with indices of adiposity and sex in healthy, adult client owned cats. BMC Vet Res, 2019. 15(1): p. 332.
9. Öhlund, M., et al., Incidence of Diabetes Mellitus in Insured Swedish Cats in Relation to Age, Breed and Sex. J Vet Intern Med, 2015. 29(5): p. 1342-7.
10. Niessen, S.J., et al., Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter. PLoS One, 2015. 10(5): p. e0127794.
11. Valentin, S.Y., et al., Clinical findings, diagnostic test results, and treatment outcome in cats with spontaneous hyperadrenocorticism: 30 cases. J Vet Intern Med, 2014. 28(2): p. 481-7.
12. Linderman, M.J., et al., Feline exocrine pancreatic carcinoma: a retrospective study of 34 cases. Vet Comp Oncol, 2013. 11(3): p. 208-18.
13. Lien, Y.H., H.P. Huang, and P.H. Chang, Iatrogenic hyperadrenocorticism in 12 cats. J Am Anim Hosp Assoc, 2006. 42(6): p. 414-23.
14. Niessen, S.J., D.B. Church, and Y. Forcada, Hypersomatotropism, acromegaly, and hyperadrenocorticism and feline diabetes mellitus. Vet Clin North Am Small Anim Pract, 2013. 43(2): p. 319-50.
15. Fleeman, L. and R. Gostelow, Updates in Feline Diabetes Mellitus and Hypersomatotropism. Vet Clin North Am Small Anim Pract, 2020. 50(5): p. 1085-1105.
16. Albuquerque, C.S., et al., Priorities on treatment and monitoring of diabetic cats from the owners’ points of view. J Feline Med Surg, 2020. 22(6): p. 506-513.
17. Zoran, D.L. and J.S. Rand, The role of diet in the prevention and management of feline diabetes. Vet Clin North Am Small Anim Pract, 2013. 43(2): p. 233-43.
18. Michel, K. and M. Scherk, From problem to success: feline weight loss programs that work. J Feline Med Surg, 2012. 14(5): p. 327-36.
19. Bennett, N., 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(2): p. 73-84.
20. Frank, G., et al., Use of a high-protein diet in the management of feline diabetes mellitus. Vet Ther, 2001. 2(3): p. 238-46.
21. Zini, E., et al., Predictors of clinical remission in cats with diabetes mellitus. J Vet Intern Med, 2010. 24(6): p. 1314-21.
22. de-Oliveira, L.D., et al., Effects of six carbohydrate sources on diet digestibility and postprandial glucose and insulin responses in cats. J Anim Sci, 2008. 86(9): p. 2237-46.