GLP-1 therapies set to top global drug sales in 2026

GLP-1 therapies approved to treat obesity and diabetes are expected to become the world's best-selling drugs in 2026, overtaking Merck's longtime sales leader Keytruda, according to Evaluate's 2026 Preview report.

As worldwide demand for metabolic treatments continues to climb, the market's two leading GLP-1 drugs, Elli Lilly's tirzepatide and Novo Nordisk's semaglutide, are projected to generate more than $84.5 billion in combined global sales this year alone, the report forecasts.

While diabetes medications continue to underpin GLP-1 revenue, most of the market's expansion is being driven by obesity, which analysts estimate could grow into a $150 billion market by 2035.

Growth is also being fueled in part by the emergence of oral alternatives, next-generation GLP-1 therapies and expanded approvals, which are broadening the drugs' market reach.

Eli Lilly's crown jewel -- tirzepatide, branded as Mounjaro for diabetes and Zepbound for obesity -- is projected to become this year's highest-grossing drug, with tirzepatide's global sales expected to surpass $45 billion, Evaluate estimates.

Lilly's Mounjaro is poised to become the biggest incretin brand in 2026, stealing the title from Novo's type 2 diabetes drug, Ozempic, Evaluate says

Mounjaro is expected to account for a larger share of tirzepatide's forecasted revenue, with the diabetes drug on course to bring in nearly $26 billion this year.

Zepbound is slated to drive the next leg of GLP-1 growth, supported by its expanded approval for obstructive sleep apnea, with sales projected to hit up to $20 billion, the report shows.

The tirzepatide franchise took the title of the world's best-selling drug from Merck's heavyweight Keytruda last fall, after Mounjaro and Zepbound were named the two fastest-growing medicines of 2025.

Close behind is Novo Nordisk's main star semaglutide, marketed as Wegovy for obesity and Ozempic for diabetes. The GLP-1 franchise is projected to generate up to $39.5 billion in combined sales in 2026.

Diabetes is expected to remain the main driver of semaglutide sales this year, according to Evaluate.

Ozempic sales are projected to peak in 2026 and hover around $19.5 billion, while Wegovy's revenue is expected to reach roughly $15.5 billion, Evaluate indicates.

Alivia Kaylor is a scientist and the senior site editor of Pharma Life Sciences.