Abstract
Context
Both gastric emptying and the secretion of glucagon-like peptide-1 (GLP-1) are major determinants of postprandial glycemia in health and type 2 diabetes (T2D). GLP-1 secretion after a meal is dependent on the entry of nutrients into the small intestine, which, in turn, slows gastric emptying.
Objective
To define the relationship between gastric emptying and the GLP-1 response to both oral and small intestinal nutrients in subjects with and without T2D.
Design
We evaluated: (i) the relationship between gastric emptying (breath test) and postprandial GLP-1 levels after a mashed potato meal in 73 T2D subjects; (ii) inter-individual variations in GLP-1 response to (a) intraduodenal glucose (4kcal/min) during euglycemia and hyperglycemia in 11 healthy, and 12 T2D, subjects, (b) intraduodenal fat (2kcal/min) in 15 T2D subjects, and (c) intraduodenal protein (3kcal/min) in 10 healthy subjects; and (iii) the relationship between gastric emptying (breath test) of 75g oral glucose and the GLP-1 response to intraduodenal glucose (4kcal/min) in 21 subjects (9 healthy, 12 T2D).
Results
The GLP-1 response to the mashed potato meal was unrelated to the gastric half-emptying time (T50). The GLP-1 responses to intraduodenal glucose, fat and protein varied substantially between individuals, but intra-individual variation to glucose was modest. The T50 of oral glucose was related directly to the GLP-1 response to intraduodenal glucose (r=0.65, P=0.002).
Conclusions
In a given individual, gastric emptying is not a determinant of the postprandial GLP-1 response. However, the intrinsic gastric emptying rate is determined in part by the responsiveness of GLP-1 to intestinal nutrients.
A Stable Isotope Breath Test With a Standard Meal for Abnormal Gastric Emptying of Solids in the Clinic and in Research
