SUSTAIN 10 quantifies the semaglutide advantage over liraglutide

A clinical trial called SUSTAIN 10 directly compared two injectable diabetes drugs in the same class, semaglutide and liraglutide, and found semaglutide worked better on the two measures doctors watch most closely: blood sugar control and weight. The trial results were published in the journal Diabetes & Metabolism in 2020.^[1]

The study enrolled 577 adults with type 2 diabetes who were already taking one to three oral diabetes drugs. Researchers randomly assigned them to add either once-weekly semaglutide at 1.0 mg or once-daily liraglutide at 1.2 mg. Both drugs belong to the GLP-1 receptor agonist class, but semaglutide is dosed weekly while liraglutide requires a daily shot.^[1]

After 30 weeks, average A1C, a measure of long-term blood sugar, had started at 8.2% for both groups. It fell by 1.7 percentage points with semaglutide and by 1.0 percentage point with liraglutide, a statistically significant difference.^[1] Average body weight, which started at 96.9 kg (about 214 pounds), dropped by 5.8 kg (about 12.8 pounds) with semaglutide compared with 1.9 kg (about 4.2 pounds) with liraglutide.^[1] More people on semaglutide reached common treatment goals, such as an A1C under 7.0% or 6.5%, and losing 5% or 10% of body weight, than people on liraglutide.^[1]

The advantage came with tradeoffs. Gastrointestinal side effects, the most common adverse events in the trial, were more frequent with semaglutide than liraglutide, 43.9% versus 38.3%.^[1] More people also stopped treatment altogether because of side effects: 11.4% on semaglutide compared with 6.6% on liraglutide.^[1] Aside from these differences, the two drugs had broadly similar safety profiles.^[1]

Why it matters for patients

This trial did not test the higher-dose or newer versions of semaglutide sold today as Ozempic or Wegovy, and it was done in people with type 2 diabetes rather than in people using the drug specifically for weight loss. Even so, the results help explain why semaglutide-based products, including Ozempic and Wegovy, gained wider use than older liraglutide-based products such as Victoza and Saxenda. The 1.0 mg semaglutide dose tested here produced roughly triple the weight loss of liraglutide at 30 weeks in this trial.^[1]

The flip side is that more of the effect came with more stomach-related discomfort, such as nausea or vomiting, and a higher chance of quitting treatment. Nearly twice the share of patients on semaglutide stopped the drug because of side effects compared with those on liraglutide, 11.4% versus 6.6%.^[1] For someone weighing these two options, this trial suggests a tradeoff between stronger average results and a somewhat higher chance of not tolerating the medication.

The study was open-label, meaning patients and doctors knew which drug each person was taking, which can influence some outcomes, and it lasted only 30 weeks, so it does not show what happens with longer use. It also does not address cost, insurance coverage, or how these findings translate to people without diabetes who take semaglutide for weight management alone. Those questions are not addressed in this source and remain outside what this trial can answer.

What happens next

The source material does not describe any follow-up studies extending SUSTAIN 10 results beyond 30 weeks, and no dated milestones for further semaglutide-versus-liraglutide comparisons are given in this source.^[1]