Comparison of the effect of semisynthetic human insulin and porcine insulin on glucose kinetics, plasma free fatty acid and amino acid levels in man

The effect of semisynthetic human insulin on hepatic glucose output, peripheral glucose clearance, plasma levels of C-Peptide, free fatty acids and amino acids was compared with purified pork insulin using the glucose clamp technique. 8 normal overnight-fasted subjects received intravenous infusions of either human or porcine insulin at 20 mU/m2.min(-1) during 120 min achieving plasma insulin levels of approximately equal to 50 mU/l. Plasma glucose levels were maintained at euglycaemia by variable rates of glucose infusion. Hepatic glucose production measured by continuous infusion of 3-(3) H-glucose was similarly suppressed by both insulins to rates near zero. The metabolic clearance rate of glucose increased during infusion of human insulin by 120%, C-peptide levels decreased by 41% and plasma FFA concentrations fell by 74%. The respective changes during infusion of pork insulin were similar, 118%, 48% and 72%. Both insulins decreased the plasma levels of branched-chain amino acids, tyrosine, phenylalanine, methionine, serine and histidine similarly. Thus, the results demonstrate that semisynthetic human and porcine insulin are aequipotent with respect to suppression of hepatic glucose output, stimulation of glucose clearance, inhibition of insulin secretion, lipolysis and proteolysis.