DURATION-6 publishes: weekly exenatide loses to daily liraglutide

A head-to-head trial published in The Lancet on January 12, 2013, found that once-daily liraglutide worked better than once-weekly exenatide extended-release at lowering blood sugar in people with type 2 diabetes ^[1]. The study, known as DURATION-6, is one of the clearest early data points showing that GLP-1 drugs built to mimic the human version of the hormone can outperform those based on exendin-4, a compound derived from Gila monster venom ^[1].

The trial enrolled 912 adults with type 2 diabetes who were already on lifestyle changes and oral diabetes drugs, and randomly assigned them to add either liraglutide 1.8 mg once daily or exenatide extended-release 2 mg once weekly ^[1]. The study ran for 26 weeks at 105 sites in 19 countries between January 2010 and January 2011, and both patients and researchers knew which drug each person was taking ^[1]. Of the 911 patients included in the main analysis, 450 got liraglutide and 461 got exenatide ^[1].

After 26 weeks, A1C, a measure of average blood sugar, dropped by 1.48 percentage points in the liraglutide group compared with 1.28 points in the exenatide group ^[1]. That 0.21-point gap did not meet the study's predefined bar for showing exenatide was "not worse" than liraglutide, meaning exenatide formally lost the comparison ^[1]. A companion commentary published alongside the trial noted the result as a meaningful data point for choosing between the two drugs ^[1].

The tradeoff showed up in side effects. Nausea affected 21 percent of people on liraglutide but only 9 percent of those on exenatide; diarrhea hit 13 percent versus 6 percent, and vomiting 11 percent versus 4 percent, all more common with liraglutide ^[1]. Both drugs' side effects eased over time, and few patients quit the study because of them: 5 percent on liraglutide and 3 percent on exenatide ^[1]. The trial was funded by Eli Lilly and Amylin Pharmaceuticals, which marketed exenatide at the time ^[1].

Why it matters for patients

This 2013 trial does not involve any of the drugs most Americans associate with GLP-1 therapy today, such as Ozempic, Wegovy, Mounjaro, or Zepbound. It compares two older type 2 diabetes drugs: liraglutide, later sold as Victoza and, at a higher dose, as the weight-loss drug Saxenda, and exenatide extended-release, sold as Bydureon ^[1]. Still, the result mattered because it was among the first solid trial evidence that drugs built on the human GLP-1 backbone could beat exendin-based drugs on blood sugar control, a pattern that would echo years later when semaglutide and tirzepatide, both human-based designs, outperformed older options in later trials ^[1].

For someone weighing an older GLP-1 drug against a newer one, the practical lesson from this trial is that better blood sugar control and fewer injections do not always come in the same package. Exenatide's once-weekly dosing was more convenient, but it caused less nausea and vomiting than daily liraglutide, even though it controlled blood sugar less well ^[1]. That kind of tradeoff between effectiveness, dosing frequency, and stomach side effects remains a live consideration in choosing among GLP-1 medications today, though the specific drugs available and their comparative data have changed considerably since 2013.

What happens next

The sources here do not describe follow-on studies or regulatory actions tied to DURATION-6 itself. What is not yet known from these sources is how this early result influenced later development or marketing decisions for the diabetes and obesity drugs available now.