Study 1. R d was estimated, assuming attainment of steady state, from the measured plateau plasma 3H-glucose concentration (c P) and corresponding measured plasma glucose concentration (C P) using R d = I × C P/c P where I is tracer infusion rate. The reported basal R d value represents the average of the 60, 70, and 80 min estimates. The reported clamp R d value was calculated from the average of the 140, 150, and 160 min estimates. During the basal phase, HGO was calculated as HGO = R d. During the clamp phase HGO was calculated as HGO = R d − GIR, where GIR is the steady state glucose infusion rate.
