Plasma Insulin Response to Oral and Intravenous Glucose Administration1

TLDR

The study introduces a new method to assess glucose metabolism in humans using an oral glucose load. The method involves administering 20 g of glucose orally and intravenously to 10 healthy adults, measuring blood glucose disappearance rate constants (K) and plasma insulin levels during and for one hour after a one‑hour constant infusion. Blood glucose concentrations and K values were similar for oral and intravenous administration, but plasma insulin responses differed, with oral glucose causing a significant, sustained rise and intravenous glucose producing a smaller, transient increase.

Abstract

This paper describes a new method for evaluating glucose metabolism in man using an oral glucose load. The procedure permits the calculation of a blood glucose disappearance rate constant (K) and thereby makes it possible to compare quantitatively the response to oral and intravenous glucose administration in a given individual. Ten metabolically normal adult humans were studied under carefully controlled conditions. Each received similar amounts (20 g) of glucose both orally and intravenously (2–7 days apart) by constant infusion for 1 hr. The effects on blood glucose disappearance rate constants (K) and plasma insulin concentrations (immunoassay) during and for 1 hr following the infusion were compared. Blood glucose concentrations and K values with the 2 routes of glucose administration were similar. In contrast, plasma insulin responses showed a significant difference: oral glucose resulted in a significant and sustained rise, whereas intravenous glucose was associated with a smaller and transient inc...