GLP-1 and DPP-4 Mechanism of Action and Clinical Applications

Introduction to GLP-1 and DPP-4

The American Diabetes Association notes that GLP-1 stimulates glucose-dependent insulin secretion, suppresses glucagon secretion, delays gastric emptying, and decreases appetite, while DPP-4 inhibitors increase the levels of circulating GLP-1 by blocking the enzyme that degrades it 1

The European Association for the Study of Diabetes recommends that GLP-1 receptor agonists, which mimic the effects of endogenous GLP-1, can delay gastric emptying and increase feelings of fullness, contributing to weight loss 2
The American College of Cardiology notes that DPP-4 inhibitors improve glucose-dependent insulin secretion and reduce glucagon secretion by increasing the levels of active GLP-1 and GIP, with a strength of evidence rated as high 1

The American Association of Clinical Endocrinologists states that GLP-1 receptor agonists provide a greater reduction in HbA1c (0.5-1.5%) compared to DPP-4 inhibitors (0.4-0.9%), with a moderate strength of evidence 3
The International Diabetes Federation recommends that GLP-1 receptor agonists promote weight loss, while DPP-4 inhibitors are generally weight-neutral, with a low strength of evidence 3

The National Institute for Health and Care Excellence suggests that DPP-4 inhibitors can be used as monotherapy or in combination with other antidiabetic medications, with a high strength of evidence 1
The American Heart Association recommends that for patients with type 2 diabetes and chronic kidney disease with an eGFR ≥30 mL/min/1.73 m², treatment with metformin and an SGLT2 inhibitor is recommended as first-line therapy, with a high strength of evidence 4
The European Society of Cardiology notes that DPP-4 inhibitors have a minimal risk of hypoglycemia when used as monotherapy, but caution is advised when combined with insulin, with a moderate strength of evidence 1
The American Gastroenterological Association reports that some DPP-4 inhibitors (saxagliptin and alogliptina) have been associated with an increased risk of hospitalization for heart failure, with a low strength of evidence 1

The American Diabetes Association recommends against combining DPP-4 inhibitors with GLP-1 receptor agonists or dual GIP and GLP-1 receptor agonists due to lack of additional glucose lowering beyond that of a GLP-1 receptor agonist alone 5, 6

The 2025 American Diabetes Association Standards of Care state that GLP-1 receptor agonists provide superior HbA1c reduction compared to DPP-4 inhibitors, with a reduction of 0.5-1.5% versus 0.4-0.9% respectively, although the specific comparison is not directly cited here 7
The American Diabetes Association and European Association for the Study of Diabetes consensus warns against prescribing GLP-1 receptor agonists and DPP-4 inhibitors in combination 7

The American Diabetes Association recommends switching from a DPP-4 inhibitor to a GLP-1 receptor agonist or dual GIP/GLP-1 receptor agonist rather than adding them together when a patient needs intensification 7, 5
The American Diabetes Association prefers GLP-1 receptor agonists, including dual GIP/GLP-1 agonists, over DPP-4 inhibitors when injectable therapy is acceptable, given their superior efficacy for glucose lowering, weight reduction, and cardiovascular benefits 5, 6
When combining with insulin, the American Diabetes Association recommends using the GLP-1/GIP receptor agonist with insulin rather than DPP-4 inhibitor with insulin, as this provides greater glycemic effectiveness and beneficial effects on weight and hypoglycemia risk 5, 6

The American Diabetes Association and European Association for the Study of Diabetes warn against assuming that combining DPP-4 inhibitors and GLP-1 receptor agonists will have additive effects, as the GLP-1 receptor agonist overshadows any benefit from DPP-4 inhibition, making the combination wasteful and exposing patients to unnecessary medication costs and potential side effects from the DPP-4 inhibitor 7, 5, 6

Saxagliptin and alogliptin increase heart failure hospitalization risk by 27% in high-risk patients, according to the American Heart Association guidelines 8, 9
DPP-4 inhibitors show higher heart failure risk compared to GLP-1 receptor agonists (HR 1.22, 95% CI 1.05-1.42), as reported by the American College of Cardiology 8