Among once-weekly GLP-1 receptor agonists, semaglutide showed superior reductions in blood sugar and body weight compared to exenatide ER and dulaglutide in head-to-head clinical trials.
Semaglutide superior in head-to-head trialsIn direct comparisons, semaglutide produced greater reductions in both HbA1c and body weight than exenatide ER and dulaglutide, establishing it as the most effective weekly GLP-1 RA.
What the researchers found
Once-weekly GLP-1 receptor agonists effectively lower HbA1c and body weight in type 2 diabetes with a low risk of hypoglycemia. Semaglutide showed the greatest reductions in both HbA1c and body weight in head-to-head comparisons with exenatide ER and dulaglutide. Exenatide ER and dulaglutide demonstrated similar or superior efficacy to oral antidiabetic drugs. All once-weekly GLP-1 RAs were effective as both monotherapy and add-on therapy to various background medications including insulin. Gastrointestinal side effects (nausea, vomiting, diarrhea) were the most common adverse events.
Why it matters
The shift from daily to weekly injections was a major advance in GLP-1 peptide therapeutics, improving patient convenience and adherence. This review compares the three weekly GLP-1 RAs available at the time and highlights semaglutide's emerging superiority — foreshadowing its rise to become the most widely prescribed drug in this class. Understanding the comparative efficacy of these peptide drugs helps guide clinical decision-making.
The numbers in context
3 weekly GLP-1 RAs compared (exenatide ER, dulaglutide, semaglutide) · semaglutide superior for A1c and weight vs exenatide ER and dulaglutide · low hypoglycemia rates · GI adverse events most common · effective as monotherapy and combination therapy
How the study worked
This is a narrative review and supplement article synthesizing data from clinical trials of once-weekly GLP-1 receptor agonists including exenatide ER, dulaglutide, and semaglutide. It covers monotherapy data, head-to-head comparisons, add-on therapy with various background medications, and safety profiles.
Who was studied
Review of clinical trial data in adults with type 2 diabetes treated with once-weekly GLP-1 receptor agonists
What this study cannot tell us
This supplement was funded by Novo Nordisk (semaglutide manufacturer), and most authors reported financial relationships with pharmaceutical companies. The review was published before the full scope of semaglutide's clinical program was complete, so longer-term and cardiovascular outcome data were not fully available. Head-to-head trial comparisons have limitations including different baseline patient characteristics.
How to read the evidence
This is a narrative review summarizing data from randomized controlled trials, including head-to-head comparative studies. However, it was industry-funded (Novo Nordisk) and most authors had financial ties to pharmaceutical companies, which should be considered when interpreting the conclusions.
When this study was published
Published in 2018, this review represents an early comparative assessment of weekly GLP-1 RAs. Since then, semaglutide has received multiple additional approvals, and tirzepatide (a dual GIP/GLP-1 agonist) has entered the market as a competitor.
The bigger picture
This review captures the GLP-1 RA landscape just as semaglutide was establishing its clinical superiority, a trend that has since accelerated dramatically with approvals for obesity, cardiovascular risk reduction, and MASH. The comparative data reviewed here laid the groundwork for semaglutide's emergence as one of the most prescribed drugs in the world.
Questions still open
- How does the newer dual GIP/GLP-1 agonist tirzepatide compare to semaglutide in head-to-head trials?
- Does semaglutide's superior efficacy come with higher rates of gastrointestinal side effects?
- Are there patient subgroups who respond better to exenatide ER or dulaglutide than semaglutide?
Common questions
Why is weekly dosing important for GLP-1 drugs?
If semaglutide is the most effective, why would a doctor prescribe a different GLP-1 drug?
Read the original research
Glycemic Efficacy, Weight Effects, and Safety of Once-Weekly Glucagon-Like Peptide-1 Receptor Agonists.
Journal of managed care & specialty pharmacy, 24(9-a Suppl), S14-S29
Citation
Handelsman, Yehuda; Wyne, Kathleen; Cannon, Anthony; Shannon, Michael; Schneider, Doron. (2018). Glycemic Efficacy, Weight Effects, and Safety of Once-Weekly Glucagon-Like Peptide-1 Receptor Agonists.. Journal of managed care & specialty pharmacy, 24(9-a Suppl), S14-S29. https://doi.org/10.18553/jmcp.2018.24.9-a.s14