This article is a review of the state of science in 2008 regarding the relationship of dry cat food diets to diabetes mellitus and obesity. It was written by a DVM/PhD faculty at The Ohio State University vet school with significant research publications related to cats, see: http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=DetailsSearch&Term=Buffington+CA[Author]+AND+%20%22last%2010%20years%22[dp] Dr. Buffington is a co-author of the book "Manual of Veterinary Dietetics," and one of the founders of "The Indoor Cat Initiative" (now "The Indoor Pet Initiative") which can be found on at: http://indoorpet.osu.edu The bottom line of the article is that this researcher--extremely familiar with the published literature--says that evidence from research studies currently indicates that carbs in dry food are NOT ASSOCIATED with either diabetes mellitus or obesity in cats. Instead, research indicates that environmental factors like lack of execise and being overweight, along with genetics, are what predispose cats to DM and other weight-related medical conditions. Here are some key selected quotes from the article: "A commonly raised issue with regard to cat foods is the suitability of carbohydrates in dry foods for cats. Cats are recognized to have evolved as obligate carnivores, consuming foods (small mammals, insects, birds) containing mostly water, protein, and relatively little carbohydrate or fat. Studies have shown that cats are less efficient than some other mammals are at metabolizing dietary carbohydrates under certain circumstances. This observation appears to have led to speculation that long term feeding of carbohydrates may have detrimental effects on the health of cats. Concerns have been raised that some association between the carbohydrate content of dry cat foods and risk of obesity and type 2 diabetes mellitus (DM) may exist, although the relationship, if any, is far from clear." "Whether these and other nutritional peculiarities of domestic cats (5) make dry diets unsuitable for them is far from obvious. Although concern is occasionally expressed about feeding “high carbohydrate” diets, the terms “high” and “carbohydrate” are rarely defined clearly. The carbohydrate content of contemporary North American dry cat diets appears to be in the range of 4.5 to 12 g/100 kcal (6). Martin and Rand (7) reported that neutered, sedentary, confined cats consumed approximately 80 kcal/kg body weight (BW)/d (client-owned cats often consume even less than this in my clinical experience), so a 5-kg cat might consume approximately 400 kcal, or about 18 to 48 g of carbohydrate; roughly 4 to 10 g of carbohydrates/kg BW/d. Cats commonly consume small, multiple meals daily. Martin and Rand (7) reported that the cats they studied consumed a median of 9 meals/d; other reports (5) indicated that cats may eat even more frequently, so cats may ingest less than 1 g of carbohydrate/leg BW per meal, even when fed a diet containing the largest quantity of carbohydrate. At this range of carbohydrate content, 2 studies (7,8) have reported that intake of dry carbohydrate (as starch or ground grain)—containing cat diets did not alter blood glucose concentrations." "Based on the available evidence, it does not appear that obesity or DM represent diet-induced diseases in cats. In 1994, an epidemiological investigation reported evidence for an increased risk of obesity in cats fed commercially available, high-carbohydrate, dry-expanded diets as opposed to commercially available, canned, high-fat diets (11). However, subsequent studies have not been able to replicate these results. Robertson (12) reported that the make-up of a cat’s diet was not associated with its weight or weight category. He did find that overweight cats were more likely to be cross-bred, (odds ratio [OR] = 2.1), neutered (OR = 2.8), living in houses with only 1 or 2 cats (OR = 1.8), male (OR = 1.4), and predominantly confined inside a house (OR = 1.4). He concluded that obesity was influenced by a variety of factors related to the animal, the diet, and the management of the animal. In a recent population-based study of disease prevalence among 469 cats in the United States and Australia, 1 case of obesity (0.2%) and 7 cases of DM (1.5%) were identified. The prevalence of DM in cats may be compared to the population prevalence of ~5.5% in humans (13). One might have expected a significantly higher prevalence of DM in cats if the disorder was caused solely by an unsatisfactory diet. In contrast, a study of 8159 adult cats presented to veterinary practices identified 522 obese cats (6.4%) and 12 (2.3%) with DM." "In addition to the epidemiologic data, experimental studies have also found that carbohydrates per se may not be a major disease risk factor for cats. Thiess et al (14) recently conducted a short feeding trial of diets differing in carbohydrate and fat content on 6 intact and 6 neutered adult male cats. The “high carbohydrate” diet contained 9.7 g carbohydrate, 3.7 g fat, and 9 g protein/100 kcal, whereas the “high fat” diet contained 2.6 g carbohydrate, 5.9 g fat, and 10 g protein/100 kcal. They found that both diets were highly digestible, but that the cats fed the high fat diet showed a slightly elongated glucose clearance and reduced acute insulin response to glucose administration. These findings suggest diminished pancreatic insulin secretion, beta-cell responsiveness to glucose, or both in cats fed the high fat diet. Another recent study provided additional evidence that high dietary fat, but not carbohydrates, induced weight gain and increased insulin concentrations in cats, although plasma glucose concentrations were not affected by dietary fat percentage, neutering or weight gain (15)." "Evidence is somewhat stronger for disorders having a nutrient-sensitive component in cats (10,12). Rand et al (10) summarized an impressive amount of evidence for roles that genetic and environmental factors play in feline DM. Evidence for genetic factors in feline DM included the overrepresentation of Australian-bred Burmese cats in the Australian cat population. Environmental risk factors in domestic or Burmese cats included advancing age, obesity, male gender, neutering, drug treatment, physical inactivity, and indoor confinement. However, even in Burmese cats, diet was not found to be a significant risk factor for development of DM (16). In addition, these environmental factors have also been linked to a variety of chronic diseases in cats (17)." "In a recent epidemiological study, Slingerland et al (19) collected information on dietary history and physical activity of 96 cats with DM and 192 matched controls using a telephone questionnaire. They found that the percentage of dry food in the diet was not significantly correlated with the development of DM (P = 0.29), whereas both indoor confinement (P = 0.002) and low physical activity (P = 0.004) were, further eroding support for the notion that the proportion of dry food in a cat’s diet is an independent risk factor for the development of DM." "Current published evidence thus does not support a direct role for diet in general, or carbohydrates in particular, on disease risk in domestic cats. However, available evidence does suggest that environmental and developmental factors may play a larger role in the development of chronic disease in cats than previously appreciated. If so, it may explain the focus on dry foods, which are very commonly fed to indoor-housed cats, and so might be expected to co-vary with other factors." "The data also suggest that cats may be yet another species to be affected by the global epidemic of obesity and DM (26). This epidemic, also known as ‘diabesity,’ is thought to be an unintended consequence of the pronounced changes in environment, lifestyle, and behavior that have accompanied globalization (26). In addition to humans and cats, evidence suggests that the epidemic has affected horses (27) and other species as well (Zimmet 2008, personal communication)."