Effect of small intestinal glucose load on plasma ghrelin in healthy men

Postprandial ghrelin suppression arises from the interaction of meal contents with the small intestine and may relate to elevations in blood glucose and/or plasma insulin. We sought to determine whether the suppression of ghrelin by small intestinal glucose is dependent on the glucose load and can be accounted for by changes in blood glucose and/or plasma insulin. Blood glucose, plasma insulin, and plasma ghrelin levels were measured in 10 healthy males (aged 32 ± 4 yr; body mass index: 25.1 ± 0.4 kg/m²) during intraduodenal glucose infusions at 1 kcal/min (G1), 2 kcal/min (G2), and 4 kcal/min (G4), as well as intraduodenal hypertonic saline (control) for 120 min. There was a progressive decrease in ghrelin with all treatments, control at 45 min and between 90 and 120 min (P < 0.05) and G1 (P < 0.05), G2 (P < 0.0001), and G4 (P < 0.0001) between 30 and 120 min to reach a plateau at ∼90 min. There was no difference in plasma ghrelin between G1, G2, or G4. Control suppressed ghrelin to a lesser extent than intraduodenal glucose (P < 0.05). The suppression of ghrelin was not related to rises in blood glucose or plasma insulin. Suppression of ghrelin by intraduodenal glucose in healthy males is apparently independent of the glucose load and unrelated to blood glucose or insulin levels.