Insulin Sensitivity and β-Cell Function in Healthy Cats: Assessment with the Use of the Hyperglycemic Glucose Clamp

Abstract

A hyperglycemic clamp (HGC) was developed for use in conscious cats. In 21 healthy, normal glucose tolerant cats glucose disposal rate (M), insulin sensitivity (ISI (HGC)), and beta-cell response (I) at arterial plasma glucose of 9 mmol.l (-1) were measured. The HGC was tolerated well and steady state glucose infusion was achieved. Compared to values reported for humans, M values for the cats were low, which appeared to relate to both a low ISI (HGC) and a low I. HGC measures correlated with fasting plasma glucose and insulin concentrations as well as with their HOMA (homeostasis model assessment) and QUICKI (quantitative insulin sensitivity check index) counterparts. Also, I and ISI (HGC) correlated with their counterparts derived from intravenous glucose tolerance tests. In conclusion, this is the first report of hyperglycemic glucose clamping in cats. The procedure (HGC) allows for measurements of glucose disposal, beta-cell response and insulin sensitivity. Compared to human data, both insulin sensitivity and insulin secretion appeared to be low in cats. This is compatible with the carnivorous nature of this species, for which insulin resistance would be advantageous during periods of restricted food availability.

Normal Glucose Metabolism in Carnivores Overlaps with Diabetes Pathology in Non-Carnivores

“…The algorithms used in humans were generated from a large amount of data from human clamp studies and are not likely to be useful in other species. Lacking similar species-specific algorithms, insulin resistance in the cat or dolphin must be either measured using clamp methodology (112, 113) or inferred when glucose intolerance or reduced insulin responsiveness are detected (114, 115). …”

Effects of high‐fat and high‐carbohydrate diets on fat and carbohydrate oxidation and plasma metabolites in healthy cats

“…Conversely, several studies have shown that cats fed HF diets are more susceptible to weight gain and subsequent perturbations in glucose handling than those fed HC diets (Theiss et al, 2004;Backus et al, 2007;Slingerland et al, 2007;Coradini et al, 2011). In humans, HF diets have been shown to increase energy intake, decrease energy expenditure (via a reduction in thermic effect of feeding) and increase body fat accumulation (due to impaired autoregulation between fat intake and oxidation) (Duncan et al, 1983;Schwartz et al, 1985;Treuth et al, 2003).…”

Quantifying Insulin Sensitivity and Entero-Insular Responsiveness to Hyper- and Hypoglycemia in Ferrets

“…Thus, it is likely that the insulin infusion rates used in our ferret euglycemic hyperinsulinemic clamps represents a moderate dose, and that lesser and greater degrees of glucose infusion would be required by lower or higher insulin doses. In cats, infusion of 10 mU/kg/min required glucose infusion rate of 8 mU/kg/min [35], leading to the suggestion cats may be relatively insulin resistant compared to non-carnivorous species [36]. Our data indicate that the insulin resistance observed in cats is not shared with the ferrets in this study, though both are carnivorous domestic species.…”

“…In rats, a rise in glucose from ∼125 to 250 mg/dL produces an insulin increment rising from 6 to 80 µU/mL peaking by 10 minutes [37]. In cats, a rise in glucose from ∼110 to ∼160 mg/dL produces an insulin increment rising from 11 to 33 µU/mL peaking at 10 minutes [36]. Thus, although the timing of first phase insulin secretion in these ferrets is similar to that observed in other species, the amplitude of the response is more similar to that observed in cats [36], also a carnivore, being less than that observed in humans and rats.…”