Clamp Phase. Beginning after collection of the 80 min sample, insulin was infused at rates that were needed to perform ClampL clamps (defined previously). Arterial blood glucose was clamped at the basal level using the methods described previously. Arterial blood samples collected at ~120, 140, 150, and 160 min following commencement of the tracer administration were used to estimate the clamp phase 3H-glucose steady state. Additional plasma (~50 μL) was collected (during the basal phase at 80 min and during the clamp phase at 160 min) and stored at −20°C for later determination of glucose, insulin, free fatty acids (FFA), and triglycerides (TG).
