Eli Lilly vs Novo Nordisk: GLP-1 Market Share Battle in 2026

Two Companies, One Dominant Category

The global GLP-1 market has become one of the most closely watched segments in pharmaceuticals, with Eli Lilly (LLY) and Novo Nordisk (NVO) together accounting for the overwhelming majority of incretin-based therapies in circulation. Heading into the second half of 2026, the two companies are contesting leadership across injectable and, increasingly, oral delivery formats, in both established and emerging markets.

Lilly's Q1 2026 earnings report provided the clearest window yet into the competitive dynamics shaping this duopoly. Total company revenue grew 56% year over year, a rate that signals continued demand expansion rather than mere market share rotation.

Lilly's Q1 Numbers Anchor the Picture

Mounjaro and Zepbound, Lilly's tirzepatide-based injectable therapies for diabetes and obesity respectively, generated $12.8 billion in combined global revenue during Q1 2026. That figure represents $6.7 billion in incremental growth versus the same quarter a year earlier, a scale of expansion that few pharmaceutical product families have achieved in a single quarter.

Lilly raised its full-year 2026 revenue guidance by $2 billion, setting the new range at $82 to $85 billion. The midpoint of that range implies approximately 28% full-year revenue growth, a materially higher trajectory than most large-cap pharmaceutical peers. For full earnings detail, listen to the Eli Lilly Q1 2026 earnings breakdown at /podcasts/LLY_Q1_2026.

International Markets and Pricing Elasticity

Outside the United States, the competitive picture takes on distinct characteristics. In markets such as Brazil and Korea, Lilly claims approximately 60% GLP-1 market share, a position built on Mounjaro's availability and pricing reach. That market leadership carries a structural caveat: 75% of Mounjaro's ex-US business is paid out-of-pocket rather than through insurance or government reimbursement programs.

Out-of-pocket demand is inherently more price-elastic than covered prescriptions. When patients bear the full cost, volume is sensitive to price changes in ways that reimbursed markets are not. That dynamic places a portion of Lilly's international growth at the mercy of affordability decisions it makes in each market, rather than payer negotiations alone.

Novo Nordisk's semaglutide franchise, marketed as Ozempic for type 2 diabetes and Wegovy for obesity, competes directly across these same international corridors. Where Novo Nordisk holds reimbursement advantages or earlier market entry, its products carry structural momentum. The international race between the two companies is not yet settled.

Koundeo and the Oral GLP-1 Front

Lilly's newly approved oral GLP-1, Koundeo, represents a meaningful structural shift in the competitive landscape. Unlike prior oral GLP-1 options, Koundeo is the first incretin medicine to launch with obesity, not diabetes, as the primary approved indication. That distinction matters for how the product is positioned, prescribed, and covered by payers.

Early launch data reported at the Q1 2026 earnings call showed more than 20,000 patients treated, with approximately 80% described as new to the GLP-1 class entirely. That figure suggests Koundeo is drawing in patients who had not previously used injectables like Ozempic or Wegovy, pointing toward addressable market expansion rather than cannibalization of Lilly's injectable portfolio.

The prescriber base exceeded 8,000 at the time of the call, with one-third having never previously prescribed an oral GLP-1. That pattern indicates Koundeo is reaching physicians who were not previously active in this category, broadening the funnel on both the prescriber and patient side simultaneously.

Access Milestones and Medicare Coverage

Commercial access has moved quickly following Koundeo's launch. The drug secured formulary coverage at two of the three largest pharmacy benefit managers effective mid-May 2026. That level of PBM access, achieved within weeks of launch, reflects strong early payer engagement with the obesity-first positioning.

For Medicare-eligible patients, Lilly's Medicare Bridge program for Koundeo offers $50 monthly copays for eligible seniors. The program has been extended through 2027, providing pricing certainty for a population that has historically faced significant barriers to GLP-1 access due to Medicare coverage limitations on obesity treatments.

Generic Semaglutide and Category Growth

Generic versions of semaglutide have entered certain markets, most notably India. Rather than displacing branded GLP-1 therapies in established markets, generic availability at lower price points appears to be stimulating overall category awareness and patient initiation, drawing in patients who would not previously have accessed GLP-1 treatment at branded prices.

For Novo Nordisk, widespread generic semaglutide entry represents both a pricing pressure on its branded franchise and a form of market development in cost-sensitive geographies. The net effect on semaglutide revenues will depend on how aggressively Novo Nordisk competes on price in those markets against its own compound.

For Lilly, tirzepatide is structurally differentiated from semaglutide. Generic semaglutide growth that increases overall category familiarity may widen the patient population considering GLP-1 therapies, a share of which flows toward tirzepatide-based options like Mounjaro and Zepbound rather than toward the generic itself.

What the Numbers Signal for the Second Half

Lilly's guidance raise, to a range of $82 to $85 billion for full-year 2026, reflects management confidence in the durability of GLP-1 demand through the remainder of the year. The $2 billion increase was taken after Q1 results that already outpaced prior expectations, lending the raised range a degree of underlying credibility.

The forward-looking variables are more nuanced. Koundeo's oral format and obesity-first positioning open a segment of the market that injectables have not fully captured. Novo Nordisk's oral semaglutide program represents its own answer to the oral format question, and the two companies are now competing across delivery mechanisms as well as molecular profiles.

International pricing elasticity, PBM formulary decisions, and the pace of Medicare coverage expansion will shape which company accumulates share in the second half of 2026 and into 2027. Lilly's Q1 data establishes a high baseline; whether that trajectory holds depends on execution in exactly these areas. For Novo Nordisk's competitive positioning, see the Novo Nordisk Q1 2026 earnings breakdown at /podcasts/NVO_Q1_2026. Additional healthcare and pharma earnings coverage is available at /groups/healthcare.

• Lilly Q1 2026 revenue grew 56% year over year; Mounjaro and Zepbound combined for $12.8 billion in global revenue
• Full-year 2026 guidance raised by $2 billion to $82 to $85 billion, implying approximately 28% growth at the midpoint
• Koundeo is the first incretin medicine launched with obesity as the primary indication; early data shows 20,000+ patients with approximately 80% new to the GLP-1 class
• Over 8,000 prescribers had written Koundeo by the time of the Q1 call, with one-third having never previously prescribed an oral GLP-1
• Lilly holds approximately 60% GLP-1 market share in markets like Brazil and Korea; 75% of ex-US Mounjaro volume is paid out-of-pocket
• Listen to the Eli Lilly Q1 2026 and Novo Nordisk Q1 2026 episodes for full earnings detail