High chromium yeast supplementation improves glucose tolerance in pigs by decreasing hepatic extraction of insulin

Twenty Landrace x Yorkshire cross pigs (body wt, 47.9 +/- 2.9 kg) were used to evaluate effects of dietary high chromium (Cr) yeast supplementation on plasma kinetics of glucose, insulin and C-peptide, Pigs were provided free access to either a control diet (C) containing 204 mu g Cr/kg or a diet su pplemented with an additional 200 mu g Cr/kg as high Cr yeast (CR) for betw een 23 and 30 d, After overnight food deprivation, dextrose (500 g/L) was i nfused through a jugular vein catheter at a dose of 0.5 g glucose/kg body w eight with an infusion rate of 10 g glucose/min within 6 min. High Cr yeast supplementation did not affect body weight gain or food intake. There were no differences in fasting plasma concentrations of either glucose or C-pep tide, although basal plasma concentration of insulin tended to be higher in pigs fed CR (P < 0.10), Plasma glucose concentrations were lower (P < 0.01 ) at postinfusion times 5, 10, 15 and 20 min in pigs fed CR, Plasma insulin concentrations in pigs fed CR were higher (P < 0.05) at 2 and 0 min before the completion of dextrose infusion. However, the increase in plasma insul in concentrations was not accompanied by a comparable elevation in plasma C -peptide concentrations. The 30-min (postinfusion) area of plasma glucose c oncentrations tended to be lower (P < 0.10) in pigs fed CR, but there were no differences in 30-min areas of either plasma insulin or plasma C-peptide concentrations between treatments. Plasma clearance rates of glucose, insu lin and C-peptide were higher and their half-lives shorter (P < 0.05) in pi gs fed CR. In conclusion, dietary high Cr yeast supplementation improved gl ucose tolerance, possibly through a decrease in hepatic extraction of insul in.