The GLP-1 drug market, vital for diabetes and obesity treatments, is undergoing a seismic shift—most notably Novo Nordisk GLP-1 market share loss to rising competitors like Eli Lilly. This article unpacks the key forces and feedback loops behind Novo Nordisk GLP-1 market share loss in the booming GLP-1 sector. By examining how misjudged demand forecasts opened the door for rival expansion, we offer actionable insights to help pharma leaders recalibrate strategy and stay competitive in a rapidly evolving therapeutic space.

Background: The GLP-1 Arena

GLP-1 drugs, originally for type 2 diabetes, are now obesity game-changers, with the market eyed to top $100 billion by 2030. Novo Nordisk led with Ozempic (diabetes) and Wegovy (obesity), holding a 69% global share in Q2 2024. But Eli Lilly’s Mounjaro and Zepbound (both tirzepatide-based) are closing in fast, posting $3.01 billion in Q2 2024 sales with explosive growth (215.5% YoY for Mounjaro, 140% quarterly for Zepbound).

Key Drivers and Feedback

Here’s a clear breakdown of what’s fueling Novo Nordisk GLP-1 market share loss and how competitors capitalized.

1. Misjudging Demand

• What Happened: Novo Nordisk underestimated the skyrocketing demand for GLP-1 drugs, especially for weight loss. Wegovy sales hit $2.6 billion in Q1 2025 (up 85% YoY) but dropped 13% from Q4 2024 due to supply shortages.
• Impact: Stockouts left patients and doctors frustrated, with Wegovy on the FDA shortage list into late 2024, pushing customers away.
• Feedback: Supply Crunch Cycle
  • Short supply → Limited access → Unhappy patients → Switch to rivals like Zepbound → Shrinking market share → Rush to boost production → Delays in scaling up → Ongoing shortages.
  • Takeaway: This cycle turned a planning misstep into a lasting hit to Novo’s position.

2. Rivals Seize the Opening

• What Happened: Eli Lilly jumped on Novo’s supply woes, ramping up Mounjaro and Zepbound output and marketing. Zepbound hit blockbuster status in Q2 2024, with 140% quarterly growth.
• Impact: Lilly’s tirzepatide outperformed, cutting weight by up to 21% versus Wegovy’s 15%. Smart moves like lower-priced Zepbound vials and direct-to-consumer sales pulled share from Novo.
• Feedback: Competitor Surge
  • Novo’s shortages → Lilly’s ready stock → Wider reach for Lilly → Stronger buzz and trust → More prescriptions for Mounjaro/Zepbound → Novo loses ground → Lilly invests more in growth → Bigger lead.
  • Takeaway: Lilly turned Novo’s gap into a springboard for dominance.

3. Edge in Innovation

• What Happened: Lilly’s tirzepatide delivered better weight loss (up to 27% over 84 weeks vs. semaglutide’s 15% over 68 weeks). Their oral GLP-1, orforglipron, also promises ease, showing 7.9% loss in 40 weeks.
• Impact: Doctors and patients leaned toward Lilly, with analysts at BMO Capital Markets in 2025 calling Lilly’s portfolio “superior,” downgrading Novo’s stock.
• Feedback: Innovation Push
  • Novo’s early lead → Lilly’s R&D step-up → Better results from Lilly → Prescriptions shift → Novo races to innovate (e.g., CagriSema) → Setbacks (22.7% weight loss vs. 25% hoped) → Lilly holds edge.
  • Takeaway: Novo’s innovation lag let Lilly reset the competitive bar.

4. Market Pressures Pile On

• What Happened: Obesity rates (138 million in the U.S.) and new uses (e.g., Zepbound for sleep apnea) spike demand. New players like Roche, Pfizer, and Amgen, plus compounding pharmacies, crowd in. Novo cuts Wegovy prices and partners with CVS to fight back.
• Impact: Price wars and knockoffs squeeze profits, with 10-15% annual price drops expected by 2027 as rivals chase coverage and access.
• Feedback: Competition Squeeze
  • New rivals and copies → Price cuts → Thinner margins for Novo → Less cash for R&D and marketing → Weaker stance → More gains for others → Rising competition.
  • Takeaway: Broader pressure turned Novo’s misstep into a market-wide challenge.

Dynamic Insights

These feedback loops—supply crunches, competitor surges, innovation gaps, and market pressures—show how Novo Nordisk’s demand miscalculation handed rivals, especially Lilly, a clear opening. Lilly’s momentum could push its share to 44% by 2031, with Novo at 36%. Modeling tools can map this, tracking supply, prescriptions, and rival moves to forecast outcomes. Novo’s $4.1 billion U.S. plant bet aims to catch up (together with expanding market access models). But delays could widen Lilly’s lead.

Action Steps for Pharma Leaders

1. Sharpen Demand Forecasts: Use advanced analytics to nail demand, dodging supply pitfalls rivals exploit.
2. Boost Capacity Fast: Scale production quickly (e.g., Novo’s $16.5 billion Catalent buy and Lilly’s $5.3 billion Indiana push to meet need).
3. Drive Breakthroughs: Pour resources into next-gen drugs (e.g., oral options) and new uses to stay ahead.
4. Lock In Position: Balance pricing and partnerships (like Novo’s CVS move) to hold share amid price wars.
5. Track the System: Leverage dynamic modeling to spot trends and adjust strategies on the fly.

Bottom Line

Novo Nordisk GLP-1 market share slipped when it misjudged demand. It created an opening for Eli Lilly and others to surge ahead with better supply, stronger results, and bold moves. This flags the need for dynamic forecasting, fast scaling, and relentless innovation to win in a crowded, high-stakes market.