Figure 1. Relationship between hepatic sinusoidal glucagon and glucose production in vivo.

A pancreatic clamp was used to keep plasma insulin basal and constant. The glucose production rate reflects the maximal effect of glucagon and was observed approximately 15 minutes after the change in the hormone level. In this way, the accompanying hyperglycemia was limited such that its inhibitory effect on glucose production was minimal. When glucagon was made deficient (i.e., 0 pg/ml), euglycemia was maintained by glucose infusion. The region shaded blue denotes the physiologic range of plasma glucagon. Figure adapted with permission from Handbook of Physiology (96).