GLP-1 Drugs Expand

GLP-1 drugs aren’t just for diabetes anymore. These medications now treat weight loss and obstructive sleep apnea too, and researchers keep finding new uses for them.

Here’s how they work. GLP-1 drugs copy a natural hormone called glucagon-like peptide-1. That hormone controls insulin release, slows digestion, and helps people feel full faster. Some newer drugs also target a second hormone receptor, GIP, which seems to boost the effect even more.

Eli Lilly’s tirzepatide shows this trend clearly. The drug goes by two different names depending on what it treats. Doctors prescribe it as Mounjaro for type 2 diabetes. They prescribe the same medication as Zepbound for weight management.

Both versions are selling fast. Mounjaro brought in $9.9 billion in the second quarter of 2026 alone. That’s a 91% jump from the year before. Zepbound wasn’t far behind, pulling in $4.9 billion, up 46% year over year.

These aren’t just impressive numbers on paper. They point to something real: more doctors are writing prescriptions for these drugs, and more patients are staying on them despite their steep cost.

Eli Lilly also has a newer product called Foundayo. Unlike Mounjaro and Zepbound, which require injections, Foundayo comes as a pill. Right now, it’s only approved for weight loss, and it hasn’t brought in much revenue yet compared to the company’s other drugs.

That could change soon, though. If Foundayo gets FDA approval for diabetes or other conditions, it might catch up quickly. Oral medications tend to appeal to patients who dislike needles or find injections inconvenient.

Meanwhile, Eli Lilly has another drug in its pipeline: retatrutide. It just finished phase 3 trials for both diabetes and weight loss, and the company plans to file for approval in early 2027.

The trial results looked strong. But it’s worth remembering that regulators haven’t reviewed the full application yet, so approval isn’t guaranteed on any particular timeline.

Eli Lilly isn’t the only company chasing this market, though. Viking Therapeutics, a smaller biotech firm, is developing its own drug called VK2735. Like tirzepatide, it targets both GLP-1 and GIP receptors.

Viking is testing two versions of VK2735 in clinical trials. The injectable form is already in phase 3 testing. An oral version should enter late-stage trials by the end of the year.

Earlier results looked promising. In phase 2 testing, the injectable version helped patients lose an average of 14.7% of their body weight in just 13 weeks. Notably, weight loss hadn’t leveled off by the end of the trial, which suggests further loss might be possible with more time.

For comparison, tirzepatide produced an average weight loss of 20.2% over 72 weeks in its own late-stage trial. That’s a much longer study period, though, so it’s hard to compare the two drugs based on these numbers alone directly.

The oral version of VK2735 also performed well in early testing. However, researchers noticed a problem: more patients dropped out of the trial due to side effects. That’s a common issue with this drug class, since gastrointestinal symptoms like nausea are fairly frequent complaints.

Discontinuation rates like these matter quite a bit. They often influence how future trials get designed, and they can affect whether regulators eventually sign off on a drug.

For now, neither version of VK2735 has regulatory approval. That means Viking Therapeutics doesn’t have any products on the market yet, unlike Eli Lilly, which already sells multiple approved GLP-1 medications.

Access remains a real issue for patients too. All these drugs require a prescription, and even approved options often run into supply shortages or insurance coverage battles. Given how common obesity and type 2 diabetes are across the country, this isn’t just a business story. It’s a public health one.

More phase 3 results are expected from both companies in the coming months. Those results will likely shape what gets approved next, and just as importantly, what becomes available to the patients who need it.