Plasma glucose and insulin levels in genetically lean and fat sheep

This study investigated whether genetically lean and fat sheep displayed di fferences in insulin and glucose statuses. Lean genotype sheep had signific antly (P < 0.05) greater basal glucose concentrations than fat genotype she ep (4.78 versus 4.52, SED = 0.104 mmol/l), although basal plasma insulin wa s not significantly different (mean 304, SEM = 37.3 pmol/l) between the gen otypes. During glucose tolerance tests (GTT), carried out at 4 levels of in jection: 0, 0.28, 1.39 or 2.78 mmol glucose/kg liveweight, the area under t he plasma insulin curve was significantly (P < 0.05) greater for fat than l ean genotype sheep, although there were no differences in any glucose param eters. There were no significant differences between genotypes in insulin o r glucose concentrations during or following glucose infusion (GINF) experi ments at 0, 0.09, 0.46 or 0.93 mmol glucose/kg live-weight/h over 3 hours. Elevated plasma insulin concentrations after a glucose tolerance test are c oncluded to be associated with increased fatness in this genetically select ed line of sheep. However, the differences in insulin and glucose levels be tween the lean and fat genotype sheep are minor, relative to the difference s in carcass composition. (C) 1999 Academic Press.