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Glucagon-like peptide-1 (GLP-1) receptor agonists and the dual GLP-1- and glucose-dependent insulinotropic polypeptide receptor co-agonist tirzepatide (referred to here collectively as "GLP-1-based therapy") are incretin-based therapies being used increasingly in the management of both type 2 diabetes and obesity. They are now recognized to have beneficial effects beyond improved glycemic control and weight loss, including cardiovascular and renal protection. GLP-1-based therapy also slows gastric emptying, which has benefits (lowering postprandial glucose), but also potential risks (eg, hypoglycemia in individuals on insulin or sulphonylurea therapy). Their effects on the gallbladder may also be beneficial, contributing to reducing postprandial triglycerides, but they also potentially increase the risk of biliary disease. In this review, we summarize the effects of GLP-1 and incretin-based therapeutics on gastric, biliary and small intestinal function. An improved understanding of these effects will optimize the use of these drugs. [ABSTRACT FROM AUTHOR]

Context Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are established therapeutics for type 2 diabetes and obesity. Among other mechanisms, they slow gastric emptying and motility of the small intestine. This helps to limit postprandial glycemic excursions and reduce chylomicron formation and triglyceride absorption. Conversely, motility effects may have detrimental consequences, eg, retained gastric contents at endoscopy or general anesthesia, potentially complicated by pulmonary aspiration or bowel obstruction. Data Acquisition We searched the PubMed database for studies involving GLP-1RA therapy and adverse gastrointestinal/biliary events. Data Synthesis Retained gastric contents at the time of upper gastrointestinal endoscopy are found more frequently with GLP-1 RAs but rarely are associated with pulmonary aspiration. Well-justified recommendations for the periprocedural management of GLP-1RAs (eg, whether to withhold these medications and for how long) are compromised by limited evidence. Important aspects to be considered are (1) their long half-lives, (2) the capacity of GLP-1 receptor agonism to slow gastric emptying even at physiological GLP-1 concentrations, (c) tachyphylaxis observed with prolonged treatment, and (d) the limited effect on gastric emptying in individuals with slow gastric emptying before initiating treatment. Little information is available on the influence of diabetes mellitus itself (ie, in the absence of GLP-1 RA treatment) on retained gastric contents and pulmonary aspiration. Conclusion Prolonged fasting periods regarding solid meal components, point-of-care ultrasound examination for retained gastric content, and the use of prokinetic medications like erythromycin may prove helpful and represent an important area needing further study to increase patient safety for those treated with GLP-1 RAs. [ABSTRACT FROM AUTHOR]

Individuals with type 2 diabetes are at high risk of postprandial falls in blood pressure (BP) (i.e., a reduction in systolic BP of ≥20mmHg, termed postprandial hypotension (PPH)), which increases the risk of falls and mortality. This study evaluated the effects of oral metformin on postprandial BP, heart rate (HR), glucagon-like peptide-1 (GLP-1) and gastric emptying (GE) in individuals with type 2 diabetes. We studied 16 subjects (5 female) before and after ingestion of a 75g radiolabeled glucose drink, after both acute (30 min) and subacute (b.i.d for 7 days) administration of metformin (850mg) or placebo, in a double-blind, randomized, crossover design. 24-hour ambulatory BP measurement following standardized meals (breakfast, lunch and dinner) was used to quantify PPH events. The primary outcome was the postprandial fall in systolic BP. We found that acute administration of metformin did not affect BP, HR, plasma insulin or GLP-1 levels, but slowed GE (P<0.001) and reduced the glycemic response to oral glucose (P<0.001). Sub-acute metformin reduced PPH events by 32% (P=0.035), in association with an increase in HR (P=0.029), slowing of GE (P<0.001), augmentation of plasma GLP-1 (P<0.001), and a reduction in plasma glucose (P<0.001) without affecting plasma insulin. Pre-prandial BP was unaffected by metformin. To conclude, in type 2 diabetes oral metformin attenuates the hypotensive response to meals, associated with stimulation of GLP-1 and slowing of GE to reduce PPH., (© 2025 by the American Diabetes Association.)