title: Duration of fasting but not diurnal variation affects the response to glucagon in healthy cats.
abstract: The role of glucagon disturbances in diabetes is increasingly recognized. Glucagon stimulation tests (GSTs) have been described in cats previously, but information is lacking on the response of cats to glucagon under specific conditions. The aim of this study was to assess a novel protocol for GST using human-recombinant glucagon and the effect of diurnal variation and duration of fasting using this protocol in healthy cats. All intravenous doses resulted in occasional vomiting and nausea, and eventually, a 20-μg/kg intramuscular dose was chosen. Five healthy cats were then used in a repeated-measures study. Cats were free-fed regularly at 7:30 AM and 5:30 PM for 30 min. In each cat, GST was performed at 7 PM after a 25-h fast (PM25), at 9 AM after a 25-h fast (AM25), and at 9 AM after a 15-h fast (AM15). Glucose and insulin concentrations were measured at -15, 0, 15, 25, 35, 45, and 60 min after stimulation. Baseline and peak concentrations were compared using the Friedman test. Baseline glucose and insulin did not differ significantly between treatment groups. Peak glucose concentrations occurred at 15 min and were significantly higher (P = 0.0085) at AM15 (mean ± standard deviation = 185.2 ± 43.0 mg/dL) vs AM25 (144.4 ± 10.5 mg/dL) and PM25 (128.0 ± 18.4 mg/dL). Similarly, peak insulin concentrations occurred at 15 min and were significantly higher (P = 0.04) at AM15 (1,911 ± 1,153 pg/mL) vs AM25 (739 ± 52 pg/mL) or PM25 (549 ± 366 pg/mL). In conclusion, prolonged fasting significantly blunted the glycemic response to glucagon compared with shorter fasting, but diurnal variation had no significant effect on glucose or insulin responses.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA. Electronic address: gilor.1@osu.edu.
authors.forename: C
authors.initials: C
authors.lastname: Gilor
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: R
authors.initials: R
authors.lastname: Glock
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gilor
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects*; D002415:Cats / Q000097:blood / Q000502:physiology*; D002940:Circadian Rhythm; D005260:Female; D005508:Food Deprivation; D005934:Glucagon / Q000494:pharmacology*; D008297:Male; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D005934:Glucagon
keywords: Diabetes; Feline; Glucagon stimulation; Glucose; Insulin; Prediabetes