Enhancement of insulin action after oral glucose ingestion.

Abstract

Previous investigations in normal humans and rats have shown an increase in insulin sensitivity and binding affinity of adipocytes isolated 1-3 h after glucose ingestion. To determine whether a rapid enhancement of the action of insulin follows glucose ingestion in vivo, the present studies have utilized 120-min 20 mU/ m2. min euglycemic insulin infusions before and after 7.5-, 15-, 25-, and 100-g oral glucose loads. Euglycemic insulin infusions after the carbohydrate challenge were begun after arterialized blood glucose and insulin values had returned to baseline. After 15-and 25-g oral glucose loads during the 20-120-min interval of insulin infusion, glucose infusion rates increased by 44±6% (P < 0.0001) and 47 ± 9% (P < 0.0002), respectively. No significant differences in arterialized glucose or insulin values existed between basal and post-glucose insulin infusions. In addition, no significant differences in hepatic glucose production or counterregulatory hormone levels were found between basal and postglucose insulin infusions. Control infusion studies including subjects who ingested saline or mannitol failed to show an increase in insulin action. Studies were carried out to mimic the insulin curve seen after 15-and 25-g oral glucose loads. Euglycemic insulin infusions after these insulin simulation studies show a 34±7% enhancement compared to baseline euglycemic insulin infusions.These results demonstrate a rapid enhancement of insulin action after oral glucose challenge in normal humans. The insulin simulation studies suggest that insulin itself either directly or through release of another factor acts on muscle to increase insulin sensitivity. The increase in insulin action demonstrated in these investigations may represent an important regulatory mechanism to modulate tissue insulin sensitivity.

Postprandial lipaemia induces an acute decrease of insulin sensitivity in healthy men independently of plasma NEFA levels

“…A study in healthy men analysed insulin sensitivity 2-3 h following an oral glucose challenge, the glucose content of which was also in the range of our meals. In that study, glucose ingestion induced a rapid enhancement of glucose disposal and whole-body insulin sensitivity [48]. Insulin sensitivity and glucose disposal were calculated when postprandial blood glucose and insulin levels returned to baseline, as in our study.…”

Improved tolerance to sequential glucose loading (Staub-Traugott effect): size and mechanisms

“…In the subjects receiving the triple tracer protocol, the ingested glucose labeled with [1-2 H]glucose was still appearing in the systemic circulation at 180 min at sizeable rates (averaging 28.7 Ϯ 3.4 mol ⅐min Ϫ1 ⅐kg FFM Ϫ1 ), slowly tending to zero thereafter. The second load labeled with [U- 13 C]glucose appeared in the circulation in amounts and time course almost superimposable to those of the first load (Fig. 4).…”

“…Increased plasma insulin response has been reported by some studies (2,3,25), but not others (1,7,14,21,23,26,30); decreased hepatic clearance of insulin (30) and enhanced insulin sensitivity (13,14) have also been proposed.…”

Randomized clinical trial of the effect of preoperative oral carbohydrate treatment on postoperative whole-body protein and glucose kinetics

“…In the present study, where all patients had the same anaesthesia protocol including epidural anaesthesia, the addition of a preoperative beverage with a high CHO content further improved protein balance. A higher dose of CHO, sufficient to release insulin, is known to have multiple effects on metabolism 27,34 , and these effects are likely to carry over to the postoperative phase, resulting in better insulin sensitivity 7,35 . This is different from the effect on insulin sensitivity exerted by the epidural blockade, where the release of adrenal stress hormones is attenuated, resulting in less insulin resistance 8 .…”