The news: Eli Lilly and Novo spent over $270 million marketing their GLP-1 drugs to prescribers between 2018 and 2025, according to an analysis of government data and interviews with physicians from The Washington Post.

• The companies made at least one GLP-1 promotional payment to more than 250,000 doctors, physician assistants, and nurse practitioners over the period—more than for any other prescription drug class.
• Spending has risen annually since 2020, reaching 140,000 individual prescribers in 2025.
• Prescribers receiving payments include leaders of prominent diabetes and obesity medical societies, and some have received upwards of $1 million over the seven years.

Zooming out: Pharma manufacturers cannot compensate doctors to induce or reward prescribing, but can pay providers for bona fide services such as consulting and research and cover certain travel and meals. In these arrangements, pharma companies educate doctors about new drugs, and some clinicians become key opinion leaders who share what they learn with other potential prescribers. Payments and other transfers of value generally must be disclosed through the federal Open Payments database.

Why it matters: Even as Novo and Lilly have generated immense sales from GLP-1 prescriptions, some believe that the GLP-1 market remains undertapped: One obesity doctor told the Post that just 11% of people with a BMI over 40 are treated with a GLP-1.

Given the sizable addressable patient population, improving physician knowledge even further could pay off significantly for drugmakers, particularly through key opinion leaders who help shape how peers think about obesity and diabetes treatment. For instance, many physicians weren’t trained in medical school to treat obesity with medication, and some still view it primarily as a matter of willpower rather than a treatable medical condition, per the Post. The American Medical Association only recognized obesity as a disease in 2013.

Implications for pharma marketers: Weight loss drugs essentially sell themselves, as the Post notes, given their proven effectiveness at helping patients lose weight. But competition between Novo and Lilly is being fought inside the exam room as much as in consumer advertising, with each racing to convince doctors its product is superior. Lilly’s Zepbound leads among injections, while Novo’s Wegovy has the early edge in oral GLP-1s. Going forward, clinical data on microdosing and maintenance dosing could help sway hesitant prescribers, particularly as doctors interviewed by the Post said their peers seek guidance on eventually weaning patients off the drugs.

In high-demand consumer drug categories, clinicians remain a key marketing channel. They have the ability to influence patients’ brand choice, but need to be equipped to answer their most common questions about side effects, dosing, and suitability. Providing credible evidence and education around those questions can give prescribers reasons to recommend one therapy over another.

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