FIG. 2.

When compared with placebo, exogenous GIP infusion not only did not lower postprandial glucose but further worsened hyperglycemia during late postprandial period (120–360 min) in patients with type 2 diabetes. GIP infusion at a pharmacologic dose (20 ng · kg⁻¹ · min⁻¹) during a mixed meal is associated with a fivefold increase in plasma GIP levels (A), an early transient increase in plasma insulin (0–60 min) (B), a late postprandial elevation of plasma glucose (120–360 min) (C), a significant early postprandial increase in plasma glucagon (0–60 min) (D), and a significant decrease in late postprandial plasma GLP-1 levels (120–360 min) (E). GIP or placebo infusion was started a time 0 and continued for 180 min. A mixed meal was given at time 0. Data are presented as means ± SE. *Significant (P < 0.05) differences between GIP versus placebo at individual time points relative to baseline at t = 0. Blue circle, placebo; orange circle, GIP.