The Staub-Traugott effect. Evidence for multifactorial regulation of a physiological function

Abstract

Previous exposure to large amounts of glucose facilitates the disposal of a subsequent load of the sugar (priming or Staub-Traugott effect). We have investigated whether, in man, the classical effect can also be induced by more physiological loads of glucose and whether a priming effect is accompanied by augmented insulin release. To facilitate interpretation of results, a second exposure to glucose was imposed at a time point following the first exposure when the subjects were again euglycaemic. Initial infusion of glucose significantly diminished the hyperglycaemia seen after the subsequent ingestion of 1.75 g/kg of glucose. The corresponding incremental insulin response was diminished while the integrated absolute levels of the hormone were unaffected by prior i.v. glucose. Initial ingestion of 0.5 g/kg of glucose slightly reduced the glycaemic but did not affect the insulin response to a second oral load. Initial ingestion of the same oral glucose load clearly facilitated the disposal of 12.5 g of glucose subsequently injected i.v. Again, this effect of priming with glucose was not accompanied by any priming effect on insulin levels. The lack of enhancement of peripherally measured insulin secretion seemed, if anything, to overestimate B-cell secretory rates since the ratio of insulin to C-peptide was increased (from 37 to 89) after priming with glucose, suggesting that the hepatic clearance of insulin was decreased during the second glucose challenge.

It is concluded that (1) facilitation of glucose disposal by previous glucose administration can be induced by amounts of glucose equivalent to those associated with meal intake, (2) enhancement of insulin release is not an obligatory component of the facilitated glucose disposal, (3) decreased hepatic clearance of insulin may accompany the Staub-Traugott effect.

Key-words:

• C-peptide secretion
• glucose homeostasis
• insulin secretion
• intravenous glucose tolerance
• oral glucose tolerance
• Staub-Traugott effect