Effect of macronutrients, age, and obesity on 6- and 24-h postprandial glucose metabolism in cats

Abstract

. Effect of macronutrients, age, and obesity on 6-and 24-h postprandial glucose metabolism in cats. Am J Physiol Regul Integr Comp Physiol 301: R1798 -R1807, 2011. First published September 21, 2011 doi:10.1152/ajpregu.00342.2011.-Obesity and age are risk factors for feline diabetes. This study aimed to test the hypothesis that age, long-term obesity, and dietary composition would lead to peripheral and hepatorenal insulin resistance, indicated by higher endogenous glucose production (EGP) in the fasted and postprandial state, higher blood glucose and insulin, and higher leptin, free thyroxine, and lower adiponectin concentrations. Using triple tracer-2 H2O, [U-13 C3] propionate, and [3,4-13 C2] glucose infusion, and indirect calorimetry-we investigated carbohydrate and fat metabolic pathways in overnight-fasted neutered cats (13 young lean, 12 old lean, and 12 old obese), each fed three different diets (high protein with and without polyunsaturated fatty acids, and high carbohydrate) in a crossover design. EGP was lowest in fasted and postprandial obese cats despite peripheral insulin resistance, indicated by hyperinsulinemia. Gluconeogenesis was the most important pathway for EGP in all groups, but glycogen contributed significantly. Insulin and leptin concentrations were higher in old than in young lean cats; adiponectin was lowest in obese cats but surprisingly highest in lean old cats. Diet had little effect on metabolic parameters. We conclude that hepatorenal insulin resistance does not develop in the fasted or postprandial state, even in long-term obese cats, allowing the maintenance of euglycemia through lowering EGP. Glycogen plays a major role in EGP, especially in lean fasted cats, and in the postprandial state. Aging may predispose to insulin resistance, which is a risk factor for diabetes in cats. Mechanisms underlying the high adiponectin of healthy old lean cats need to be further explored. nuclear magnetic resonance spectroscopy; adipocytokines; indirect calorimetry; glycogenolysis; insulin resistance; endogenous glucose production IN MAN AND IN CATS, obesity and age are factors in the development of diabetes (8, 69). As in people, the incidence of feline obesity and diabetes has increased dramatically in the past 3 decades (2,8). Obesity is now the most common nutritional disorder in cats, and diabetes is one of the most common endocrinopathies in aging cats. Little is known about the metabolic changes in obese cats and the influence of age and food intake on metabolic parameters that contribute to increasing obesity and diabetes.Cats are obligatory carnivores that naturally subsist on a high-protein and high-fat diet. It has been stated anecdotally that glycogen contributes less to glucose production in cats than other species. Rogers et al. (61) reported that cats cannot readily adapt their sources of glucose production, a notion that has been refuted by others (25,26,65,66). We have previously shown that, in fasted cats, fractional gluconeogenesis (GNG) and glycogenolysis is similar to hum...

Gluconeogenesis is associated with high rates of tricarboxylic acid and pyruvate cycling in fasting northern elephant seals

“…Pyruvate cycling, PEPCK, and CS flux were all closely correlated both early and late in the fast, much more so than has been observed in other species (6,30,42). Such close correlation suggests coordinated regulation of these pathways during the postweaning fast (Table 5).…”

Metabolic Effects of Obesity and Its Interaction with Endocrine Diseases

“…26 Additionally, both basal insulin concentrations and insulin area under the curve during IVGTT are increased in obese dogs and cats, as they are in other mammals. [26][27][28][29][30] In the aforementioned longitudinal studies of feline obesity, these changes were apparent with as little as 10% gain over lean body weight (Fig. 1).…”

Nutrition of Aging Cats

“…19,20 There are few data, however, to support these concerns. Although some studies have shown a greater postprandial blood glucose concentration or alterations in glucose tolerance in cats after ingesting of high-carbohydrate, low-protein diets, [21][22][23] other studies have found no such effects, 17,[24][25][26][27] indicating that components other than the amount of carbohydrate in the diet influence this effect. The feeding method (eg, single meal daily vs multiple meals or continuous access to food) also alters the glucose response with higher glucose peaks after a single large meal.…”