A, EGP (d 2) at baseline (after 120 min of tracer infusion, at t = 0), and averaged for the final 30 min of each glucose step. B, Glucose Rd averaged for the final 30 min of each glucose step. Studies included previous (d 1) coinfusion of naloxone (N+), without coinfusion of naloxone (N−), and controls studies with previous (d 1) coinfusion of naloxone (C+), and without coinfusion of naloxone (C). *, P < 0.05.