Class Explorer · Endocrine
Incretin-based agents
Amplify the incretin signal that makes oral glucose release more insulin than intravenous glucose does. Because the effect is glucose-dependent, insulin only rises when glucose is high, which is why hypoglycemia is not a feature.
Members
SitagliptinA quiet, well-tolerated oral agent that does not cause hypoglycemia.SemaglutideA weekly injection that changed what glucose lowering is expected to achieve.
Also in this class: Linagliptin · Liraglutide · Dulaglutide · Tirzepatide (dual GIP/GLP-1). Full pages arrive as the library grows.
Compare the members
Sitagliptin
- Route
- Oral daily
- HbA1c effect
- Modest
- Weight
- Neutral
Semaglutide
- Route
- Weekly injection or daily oral
- HbA1c effect
- Large
- Weight
- Substantial loss
Shared across the class
- Indications
- Type 2 diabetes · Obesity (GLP-1 agonists)
- Adverse effects
- Nausea (agonists) · Pancreatitis, rare · Injection-site reaction (agonists)
- Contraindications
- Personal or family history of medullary thyroid carcinoma or MEN2 (GLP-1 agonists) · Prior pancreatitis, relative
- Monitoring
- HbA1c · Weight · Gastrointestinal tolerance during dose escalation · Renal function during any illness with vomiting
What makes each agent different
- A DPP-4 inhibitor stops the enzyme that degrades native GLP-1: modest, oral, weight-neutral, well tolerated, no outcome benefit.
- A GLP-1 receptor agonist floods the receptor directly: far greater HbA1c and weight effect, cardiovascular benefit in the outcome trials, and the gastrointestinal side effects that come with it.
- The two are not combined: the agonist already saturates what the inhibitor was protecting.
Nausea on a GLP-1 agonist is dose- and titration-related, not an allergy. Slowing the escalation usually rescues the drug.
These agents delay gastric emptying, which matters to anaesthetists: it is now a routine pre-operative question.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.