Entero-pancreatic hormone secretion, gastric emptying, and glucose absorption after frequently sampled meal tests

CONTEXT: Entero-pancreatic hormone secretion has been reported during the pre-absorptive cephalic and gastric meal phases, but never with a blood sampling frequency providing a temporal resolution that allows close scrutiny and correlations with gastric emptying and glucose absorption.

OBJECTIVE: We hypothesized that entero-pancreatic hormone secretion after nutrient ingestion would be rapid and correlate with gastric emptying and glucose absorption.

METHODS: During 2 visits in a clinical research facility, 10 healthy young men ingested a 75-g glucose drink (OG) and a liquid mixed meal (LMM) (t = 0-2 minutes) on separate days. Acetaminophen and 3-O-methyl-D-glucopyranose (3-OMG) were added to the drinks to evaluate gastric emptying and glucose absorption, respectively. Arterialized venous blood was sampled (t = -30, -20, -18, -16, -14, -12, -10, -8, -6, -4, -2, 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 30 minutes). Plasma glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), gastrin, cholecystokinin (CCK), glucagon, pancreatic polypeptide (PP), 3-OMG, and glucose were measured, as were serum insulin, C-peptide, and acetaminophen.

RESULTS: Acetaminophen increased 8 minutes after OG (P < 0.001) and LMM (P < 0.05); 3-OMG, 8 minutes after LMM (P < 0.0001), 10 minutes after OG (P = 0.04); PP, 4 minutes after LMM (P < 0.03); gastrin, 6 minutes after LMM (P < 0.003) and OG (P < 0.003); CCK, 6 minutes after LMM (P = 0.0001); GIP, 8 minutes after OG (P < 0.05) and LMM (P < 0.03); glucose, 8 minutes after OG (P < 0.001); 12 minutes after LMM (P < 0.02); GLP-1, 12 minutes after OG (P < 0.01), 10 minutes after LMM (P < 0.01); insulin, 12 minutes after LMM (P = 0.02) and OG (P = 0.002); C-peptide, 12 minutes after OG (P = 0.002) and LMM (P = 0.04).

CONCLUSION: Early postprandial hormone responses show characteristic differences with regard to timing and amplitude but also great individual differences. This should be considered when interpreting mean responses and designing study protocols.