GLP-1 drugs to drive growth in obesity and diabetes treatment | AMCP Annual 2026

The rapid rise of GLP-1 receptor agonists is reshaping the pharmaceutical landscape. GLP-1 therapies — used for Type 2 diabetes and weight management — generated approximately $132 billion in sales in 2025, a 33.5% increase from 2024. Sales of GLP-1 therapies for the weight-loss indication alone increased by 131% on a CAGR (5 year compounded annual growth rate) basis, according to Scott Biggs, director, supplier services, at IQVIA. He gave his remarks at a keynote session today at the Academy of Managed Care Pharmacy (AMCP) annual meeting in Nashville.

The drugs’ rapid uptake has helped propel overall pharmaceutical market growth, which reached approximately $923 billion in 2025, up 12% from 2024. Volume, Biggs said, is driving the pharmaceutical market. Drug price changes and new product introductions accounted for only about 10% and 7%, respectively, of what is driving growth.

“In 2024, [price change] was actually a 1% deficit to the overall growth,” Biggs said. “That was driven by the cap on insulin prices that we started to see ahead of the [Inflation Reduction Act]; several manufacturers made the choice to drop down that $35 cap on insulin.”

Shifting market trends

Once considered a niche category, obesity treatment has rapidly climbed the ranks of top therapeutic areas. The category now represents nearly $42 billion in market value, fueled largely by the GLP-1 medications, which are now available as injectable and oral therapies.

Looking ahead, obesity therapies, as well as those for oncology, are expected to be growth drivers for the category. There are currently about 190 obesity-related products in the pipeline. IQVIA projects that by 2029, obesity therapies will contribute $100 billion in sales growth.

During his presentation, Biggs presented data about the top drug classes and products. Three of the top five fastest-growing products are GLP-1 therapies, with two specifically indicated for obesity. This reflects both rising demand and expanding clinical use beyond diabetes into weight management and related conditions.

The anti-obesity market is now the fourth largest, with a 4.6% market share. The top three include immunology with an 18.3% market share, antidiabetes with a 16.6% market share, and oncologics with a 15.2% market share. “Throughout last year, I watched [the anti-obesity market] move into the No. 6 market position and then the No. 5 position, and it’s now No. 4,” Biggs said. A couple of years ago, we were not talking about Mounjaro or Zepbound.”

Within diabetes, Lilly’s GLP-1 Mounjaro (tirzepatide) is the fastest-growing drug, with 2025 sales of $39.1 billion, up 67.1% from 2024. Within obesity, Lilly’s Zepbound (tirzepatide) is the fastest-growing product, with 2025 sales of $22.9 billion, up 188.7% from 2024. The next fastest-growing product within obesity is Novo Nordisk’s Wegovy (semaglutide), with 2025 sales of $18.6 billion, up 29.2% from the year before.

IQVIA’s patient analytics team conducted a study of patients taking diabetes GLP-1 products over a 1 year period. Their analysis of about 8.6 million patients who filled GLP-1 drugs at retail for diabetes over a one-year period. Of those, roughly 72% continued filling prescriptions within retail channels, in the following year. A similar analysis of 2.5 million patients studied using obesity medications in a retail setting, about 66.5% remained in retail channels after initiation, while approximately 28% dropped off treatment entirely within the first year. This drop-off may reflect cost barriers, side effects, or inconsistent insurance coverage, factors that continue to limit continued use despite strong demand.

However, adherence challenges persist. Across new chronic therapies broadly, only 29% of patients remain on treatment after one year, highlighting a systemic issue that also affects GLP-1 utilization.

Among patients with obesity, persistence appears weaker. Of the 2.5 million patients studied using obesity medications, about 66.5% remained in retail channels after initiation, while approximately 28% dropped off treatment entirely within the first year. This drop-off may reflect cost barriers, side effects or inconsistent insurance coverage, factors that continue to limit continued use despite strong demand.

Biggs also highlighted some shifting trends. Retail pharmacies remain the primary distribution channel for GLP-1 drugs, accounting for 83% of total sales. But IQVIA’s data showed about 41% of independent pharmacies did not dispense obesity-related GLP-1 medications medications in the fourth quarter of 2025, often citing profitability concerns tied to reimbursement rates.

At the same time, new direct-to-consumer programs and expanded indications, such as use in sleep apnea and metabolic conditions, are increasing access and shifting utilization patterns. These developments have also led to increased Medicare and Medicaid coverage in certain cases, particularly when GLP-1 drugs are prescribed for nonobesity indications.

Other notable data points

• Specialty now accounts for 52.6% of the overall spend in the marketplace.
• Humira (adalimumab) continues to lose sales and market share because of biosimilars.
• Stelara (ustekinumab) and Soliris (eculizumab) are beginning to see sales and market share decline following the launch of biosimilars in 2025.
• Biosimilars in development are concentrated in areas with high sales of originator products.
• More than half of new prescriptions for novel therapies go unfilled, and only 29% of patients remain on therapy for a year.
• Generic drugs account for 88% of prescriptions and 6.3% of sales.
• Generic uptake is lower for generics entering the market in the last five years than it was 10 to 20 years ago. More generic manufacturers are delaying launches than in previous years.