A charge made against feeding dry foods to cats is that the high carbohydrate (i.e. starch) content results in high blood glucose levels which over time may have detrimental health effects. The present study determined the post-meal concentrations of plasma glucose and insulin in adult cats (seven males and four females) and dogs (Labrador retrievers; four males and five females) fed dry diets with low-starch (LS), moderate-starch (MS) or high-starch (HS) levels. In a cross-over design with at least 7 d between the test meals, plasma glucose and insulin concentrations were measured following a single meal of a LS, MS and HS diet (209 kJ/kg bodyweight). Only the HS diet resulted in significant post-meal increases in plasma glucose concentration in cats and dogs although the time-course profiles were different between the species. In cats, plasma glucose concentration was significantly increased above the pre-meal concentration from 11 h until 19 h after the meal, while in dogs, a significant increase above baseline was seen only at the 7 h time point. Plasma insulin was significantly elevated in dogs 4 -8 h following the MS diet and 2-8 h after the HS diet. In cats, plasma insulin was significantly greater than baseline from 3-7 and 11-17 h after the HS diet. The time lag (approximately 11 h) between eating the HS diet and the subsequent prolonged elevation of plasma glucose concentration seen in cats may reflect metabolic adaptations that result in a slower digestive and absorptive capacity for complex carbohydrate.Key words: Feline: Canine: Glycaemia: Insulinaemia: CarbohydrateHaving evolved as a carnivore consuming a diet naturally high in animal protein and low in carbohydrate has contributed to the belief that feeding carbohydrates to cats (particularly through dry commercial pet foods in which the carbohydrate source is predominantly starch) is detrimental to the cat's health and may play a role in the pathogenesis of a number of feline disorders, most notably type 2 diabetes mellitus (DM). The mechanisms suggested to underlie the development of DM in cats fed high-carbohydrate diets include direct 'glucotoxic' effects (e.g. apoptosis of pancreatic b-cells) and gradual 'burnout' of pancreatic b-cells due to prolonged stimulation and insulin secretion in response to elevated plasma glucose concentration (1) .The carbohydrate content of manufactured dry cat foods varies widely, typically contributing between 25 and 50 % of the metabolisable energy of the diet, although, recently, dry diets with a carbohydrate content of 10 -15 % metabolisable energy have appeared on the market. The aim of the present study was to determine the post-meal profiles of plasma glucose and insulin concentrations in cats following a meal of a low-starch (LS) diet, a moderate-starch (MS) diet and a high-starch (HS) diet. A secondary aim was to carry out a species comparison of the glucose and insulin response to the same diets in dogs. Dogs also belong to the mammalian order Carnivora (but are not obligate carnivores like the...

Data from intravenous (i.v.) glucose tolerance tests suggest that glucose clearance from the blood is slower in cats than in dogs. Since different physiological pathways are activated following oral administration compared with i.v. administration, we investigated the profiles of plasma glucose and insulin in cats and dogs following ingestion of a test meal with or without glucose. Adult male and female cats and dogs were fed either a high-protein (HP) test meal (15 g/kg body weight; ten cats and eleven dogs) or a HP þ glucose test meal (13 g/kg body-weight HP diet þ 2 g/kg body-weight D-glucose; seven cats and thirteen dogs) following a 24 h fast. Marked differences in plasma glucose and insulin profiles were observed in cats and dogs following ingestion of the glucose-loaded meal. In cats, mean plasma glucose concentration reached a peak at 120 min (10·2, 95 % CI 9·7, 10·8 mmol/l) and returned to baseline by 240 min, but no statistically significant change in plasma insulin concentration was observed. In dogs, mean plasma glucose concentration reached a peak at 60 min (6·3, 95 % CI 5·9, 6·7 mmol/l) and returned to baseline by 90 min, while plasma insulin concentration was significantly higher than pre-meal values from 30 to 120 min following the glucose-loaded meal. These results indicate that cats are not as efficient as dogs at rapidly decreasing high blood glucose levels and are consistent with a known metabolic adaptation of cats, namely a lack of glucokinase, which is important for both insulin secretion and glucose uptake from the blood.