Figure 5.

The dual- and triple-tracer approaches were simultaneously used in eight healthy subjects (4). The ttrs, Ra_meal, EGP, and R_d were calculated using either Steele’s one-compartment model (1CM) or Radziuk’s two-compartment model (2CM) following the ingestion of a mixed meal containing [1-¹³C]glucose (oral tracer) at time 0 (arrow). In order to compare the triple- versus dual-tracer approach in the same subjects, the dual-tracer protocol shown in Fig. 1 was performed on two separate occasions and a third tracer ([6-¹³H]glucose) was infused at a variable rate to mimic the anticipated changes in Ra_meal on one occasion (as percent of the total meal tracer infused: −180 to 3 min: 0%; 3–8 min: 1%; 8–35 min: 24%; 35–70 min: 24%; 70–100 min: 15%; 100–160 min: 18%; 160–270 min: 15%; 270–360 min: 3%) and on the other occasion to mimic the anticipated changes in EGP (as percent of the baseline EGP tracer: −180 to 3 min: 100%; 3–8 min: 70%; 8–18 min: 55%; 18–25 min: 30%; 25–45 min: 15%; 45–70 min: 25%; 70–160 min: 35%; 160–260 min: 55%; 260–360 min: 80%).