Prevalence of Feline Diabetes Mellitus

Diabetes mellitus is a common endocrinopathy in cats. Its prevalence has risen over the last 30 years and on average reaches around 1 case per 200 cats. This increase may be directly related to the higher prevalence of obesity in cats. Feline diabetes shares many features of human type 2 diabetes (2DM) in respect to its pathophysiology, underlying risk factors and treatment strategies. General recommendations for feeding diabetic cats has changed over the last few years and now the focus is on diets relatively high in dietary protein and low in carbohydrate. It is clear that not all authors have the same understanding of the composition of high protein or low carbohydrate diets. As a general rule, these terms refer to a protein content (on DMB) of approximately 50% protein or more, and less than 15% carbohydrates. The values will be specified in the chapter when necessary. This high protein, low carbohydrate feeding regimen, combined with rigid and well supervised insulin therapy has resulted in a sharp increase in the remission rate of diabetes mellitus. The present chapter reviews the pathophysiology of feline diabetes and discusses treatment strategies, especially in light of the cats’ specific nutrient requirements and the recommended use of high protein, low carbohydrate diets.

Thomas A. LUTZ
DVM, PhD

Thomas Lutz graduated from the Veterinary School of the Free University in Berlin (FRG) in 1989. He received a first doctoral degree (Dr. med. vet.) at the Institute of Veterinary Physiology from the University of Zurich, in 1991. In 1995, he completed his PhD in feline diabetes mellitus at the University of Queensland (Brisbane, Australia) and in 1999 his Habilitation at the Institute of Veterinary Physiology in Zurich. Since 2004, he is a Professor of Applied Veterinary Physiology in Zurich. His major research areas are the neuroendocrine controls of food intake and feline diabetes mellitus. He has published over 80 scientific articles in peer-reviewed journals.

1. Prevalence of Feline Diabetes Mellitus

Diabetes mellitus (DM) is a common endocrinopathy in cats. Its prevalence has been reported to be in a range of approximately 1:400 to 1:100 ( [Panciera et al., 1990;Rand et al., 1997). Based on the number of cases presented to veterinary teaching hospitals, a retrospective study showed that the prevalence of feline diabetes increased by a factor of more than 10 over the last 30 years. While in 1970, less than 1 case in 1000 cats was reported, this number increased to more than 12 cases per 1000 cats in 1999 (Prahl et al., 2003; 2007). At the same time, however, the fatality rate decreased markedly from over 40% to less than 10% indicating that diabetic cats can be successfully treated. Part of this is certainly due to the better understanding of the pathophysiology of feline diabetes. Important risk factors for the development of the disease are age, gender, neuter status and obesity (Table 1).

Feline Diabetes Mellitus Is Associated with Obesity

The latter factor is most likely responsible for today’s increased prevalence of feline DM because feline obesity is directly associated with insulin resistance (Scarlett et al., 1994; Hoenig, 2006a; 2007a; see also Pathophysiology of Feline Diabetes), and obesity in cats is much more common in today’s cat population: at least 20% but more likely 35 - 40% of cats are considered overweight or obese (Baral et al., 2003; Lund et al., 2005; Diez & Nguyen, 2006; German, 2006).

Influence of Age

Feline DM usually affects middle-aged and older cats with a sharp increase beyond the age of 7 years. Cats below 1 year of age are 50 times less likely to develop diabetes than cats beyond the age of 10 years (Prahl et al., 2003).

Influence of Gender and Neutering

Male cats seem to be at higher risk of developing diabetes than females. While this situation is similar in humans at least before the average age of menopause, the reason for the gender difference in feline diabetes is unknown at present. The difference seems unlikely to be directly related to the concentration of sexual hormones because most male cats are castrated, and because neutering is not an independent risk factor for the development of diabetes when controlling for body weight (BW) and age (Prahl et al., 2003).

Breed Differences

Only a few studies have investigated the possible breed differences in the prevalence of feline diabetes. While a retrospective study in the USA provided no evidence for a higher prevalence in certain breeds of cats with purebred cats actually being at lower risk than mixed breed cats (Prahl et al., 2003), some studies performed in Australia reported a higher prevalence among Burmese cats (Rand et al., 1997) (Figure 1). A similar predisposition was reported from the United Kingdom (UK; McCann et al., 2007). The author is unaware of further studies so that it remains unclear whether the reported over representation of Burmese cats in Australia and the UK is a global phenomenon.

Figure 1. Burmese Cat. An Australian study and a study from the UK report that Burmese cats have a genetic predisposition to develop diabetes mellitus (Rand et al., 1997; McCann et al., 2007). However, global breed predispositions are still disputed.