RESULTS	Indirect glucose metabolism was assessed from plasma carbon-13 ( 13C ) - labeled glucose and 13C-labeled CO2 production during a tracer infusion of uniformly 13C-labeled glucose , and de novo lipogenesis was estimated from the incorporation of 13C into palmitate-very low density lipoproteins ( VLDL ) during a tracer infusion of 1 - ( 13 ) C acetate .\