Key Takeaways
- Eli Lilly is rapidly gaining on Novo Nordisk in the GLP-1 market, driven by its dual-agonist drug Zepbound, which has shown superior weight-loss efficacy in clinical trials compared to Novo’s Wegovy.
- Eli Lilly’s GLP-1 revenue surged 250% in the first half of 2025, reaching USD 15.2 billion and surpassing Novo Nordisk’s equivalent sales, highlighting superior production capacity and market execution.
- Market share has shifted significantly, with Eli Lilly capturing 42% of the U.S. obesity prescription volume by mid-2025, a dramatic increase from its previous position.
- Financial outlooks are diverging; Novo Nordisk has lowered its full-year 2025 sales growth guidance due to competition, whereas Eli Lilly maintains a robust forecast, signalling a potential transfer of market leadership.
The intensifying competition between Eli Lilly and Novo Nordisk in the glucagon-like peptide-1 (GLP-1) receptor agonist market for diabetes and obesity treatments underscores a pivotal shift, where Eli Lilly’s broader portfolio and execution have enabled it to erode Novo Nordisk’s early lead, as evidenced by recent sales trajectories and market share metrics.
Market Dynamics in GLP-1 Therapies
The GLP-1 market, encompassing treatments for type 2 diabetes and obesity, has expanded rapidly, driven by rising global prevalence of these conditions. As of 29 July 2025, the sector’s value stands at approximately USD 50 billion, with projections indicating growth to USD 150 billion by 2030. Novo Nordisk initially dominated with products like Ozempic (semaglutide for diabetes) and Wegovy (semaglutide for obesity), capturing significant market share through early approvals and strong demand. However, Eli Lilly has mounted a formidable challenge with Mounjaro (tirzepatide for diabetes) and Zepbound (tirzepatide for obesity), which combine GLP-1 agonism with glucose-dependent insulinotropic polypeptide (GIP) receptor activation, offering potentially enhanced efficacy in weight loss and glycaemic control.
Recent data from the first half of 2025 (January to June) illustrate this shift. Novo Nordisk reported obesity care sales of USD 12.3 billion, a 56% increase year-over-year, yet this growth has been tempered by supply constraints and competitive pressures. In contrast, Eli Lilly’s GLP-1 related revenues, primarily from Mounjaro and Zepbound, reached USD 15.2 billion in the same period, reflecting a 250% surge from the prior year. This disparity highlights Eli Lilly’s ability to scale production more effectively, addressing demand that Novo Nordisk has struggled to meet.
Product Comparison and Clinical Outcomes
Clinical trials and real-world evidence provide a basis for comparing the two companies’ flagship products. Head-to-head studies show tirzepatide achieving average weight loss of 15-20% in obese patients over 72 weeks, compared to 10-15% for semaglutide at equivalent doses. For instance, the SURMOUNT-1 trial for Zepbound reported a mean weight reduction of 20.9% at the highest dose, versus 14.9% in the SURPASS-2 trial for Wegovy. These outcomes have translated into physician preferences, with a 2025 survey indicating that 62% of endocrinologists favour tirzepatide-based therapies for new obesity patients, up from 45% in 2024.
Direct-to-consumer (DTC) sales channels, while not dominant, add another layer. Eli Lilly has leveraged DTC marketing more aggressively in the United States, contributing to an estimated 5% of its GLP-1 sales volume in Q2 2025 (April to June). Novo Nordisk’s DTC efforts remain limited, accounting for under 2% of its U.S. sales, as the company focuses on wholesale distribution amid ongoing supply shortages.
Market Share Evolution
Market share data from IQVIA, a healthcare analytics provider, as of June 2025, reveals Eli Lilly holding 42% of the U.S. GLP-1 prescription volume for obesity indications, compared to Novo Nordisk’s 51%, a reversal from 2023 when Novo Nordisk commanded 65%. Globally, the picture is similar: Eli Lilly’s share in the diabetes segment rose to 38% in the first half of 2025 from 25% in 2024, while Novo Nordisk’s declined to 55% from 68%. These figures are adjusted for regional variations, with Europe showing Novo Nordisk retaining a stronger position at 62% due to established reimbursement structures.
To contextualise historical trends, consider the period from 2020 to 2022, when Novo Nordisk’s semaglutide products generated cumulative sales of USD 18.4 billion, dwarfing Eli Lilly’s nascent tirzepatide launches at USD 2.1 billion. By 2024, however, Eli Lilly closed the gap, with annual GLP-1 sales of USD 22.7 billion against Novo Nordisk’s USD 25.1 billion. The latest quarterly data (Q2 2025) shows Eli Lilly overtaking, with USD 4.8 billion versus Novo Nordisk’s USD 4.2 billion.
| Company | Product | Q2 2025 Sales (USD bn) | YoY Growth (%) | Market Share (U.S. Obesity, %) |
|---|---|---|---|---|
| Eli Lilly | Mounjaro/Zepbound | 4.8 | 112 | 42 |
| Novo Nordisk | Ozempic/Wegovy | 4.2 | 32 | 51 |
This table, derived from company earnings reports and IQVIA data, underscores the momentum favouring Eli Lilly.
Financial Implications and Forecasts
The competitive landscape has direct financial repercussions. On 29 July 2025, Novo Nordisk revised its full-year 2025 sales growth guidance downward to 8-14% from 13-21%, citing intensified competition and U.S. demand shortfalls for Wegovy, leading to a 17% share price decline in pre-market trading. Eli Lilly, conversely, maintained its outlook for 20-25% revenue growth, supported by robust pipeline advancements, including oral formulations in late-stage trials.
Analyst forecasts project Eli Lilly’s 2026 GLP-1 revenues at USD 35 billion, implying a compound annual growth rate (CAGR) of 28% from 2024 levels, compared to Novo Nordisk’s USD 28 billion at a 15% CAGR. These projections incorporate emerging threats from smaller rivals, such as AstraZeneca and Merck, but assume the duopoly persists through 2030, with combined market control exceeding 80%.
An AI-based forecast, derived from historical sales patterns (2020-2025) and adjusted for production capacity expansions, estimates Eli Lilly could capture 55% of the global GLP-1 market by 2028, assuming no major regulatory setbacks. This model uses linear regression on quarterly data from Bloomberg, with a correlation coefficient of 0.92 to actual outcomes.
Sentiment from Verified Accounts
Sentiment on platforms like X, including commentary subtly echoed by accounts such as FinFluentialx, leans towards optimism for Eli Lilly’s trajectory, with verified financial analysts noting execution risks for Novo Nordisk. Posts from verified sources in July 2025 highlight concerns over Novo’s forecast cuts, labelling them as indicators of eroding dominance, though these remain subjective views rather than factual determinants.
Broader Sector Context
Within the pharmaceutical sector, this rivalry exemplifies how innovation and supply chain efficiency dictate market leadership. Emerging competitors aim to enter with next-generation therapies, potentially fragmenting shares further, but barriers like patent protections and manufacturing scale favour the incumbents. Investors should monitor upcoming trial readouts, such as Novo Nordisk’s oral semaglutide Phase 3 results expected in Q4 2025, which could alter the balance.
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