Different effects of long-chain and medium-chain triglycerides on glucose oxidation during total parenteral nutrition

This study was undertaken to clarify differences in the effects of lipid emulsions containing either long-chain or medium-chain triglycerides (MCT) on glucose metabolism during total parenteral nutrition (TPN). Glucose kinetics were assessed in beagle dogs using primed, constant infusions of [14C]- and [6-3H]glucose. The rate of appearance of glucose, the percent of VCO2 derived from the oxidation of glucose, the rate of glucose oxidation, and the percent of glucose uptake oxidized were measured at the end of 72 hours of each of the two TPN regimens, ie, TPN in which soybean oil served as long-chain triglyceride comprising 40% of nonprotein calories (L-TPN), and TPN in which tricaprylin emulsion served as MCT (M-TPN). Glucose intake was 5.9 +/- 0.5 mg/kg per minute in L-TPN and 5.8 +/- 0.2 mg/kg per minute in M-TPN. There was no significant difference in the rate of glucose appearance between L-TPN and M-TPN. The rate of glucose oxidation was higher with M-TPN than with L-TPN (p < .05). Not only the percent of VCO2 derived from the oxidation of glucose but also the percent of glucose uptake oxidized tended to be higher during M-TPN than during L-TPN. These findings suggest that the glucose metabolism of dogs receiving L-TPN is different from that of dogs receiving M-TPN.