The effects of ingested and intravenous glucose on forearm uptake of glucose and glucogenic substrate in normal man.

The forearm uptake of glucose, lactate, and alanine was determined in overnight fasted man following both oral glucose loading and the intravenous (i.v.) infusion of glucose in an absorption pattern. Arterial glucose concentrations were lower following oral than following i.v. loading and forearm glucose uptake was 50% higher after oral glucose. Arterial insulin levels were higher in the first 2 h during oral loading. Forearm lactate and pyruvate production did not change significantly during glucose administration by either route so that the increased plasma levels are due to splanchnic production.