Ozempic use quadrupled in under 3 years. Much of it is off-label.

The figure for total prescriptions is based on insurance claims and is likely an undercount. Many health plans don’t cover weight-loss drugs, leaving patients to pay for them out of pocket.

Trilliant’s analysis, which encompasses claims data for about 300 million Americans and examines health trends broadly, also found that a little more than half of patients taking Ozempic or a similar drug have a history of diabetes. That reinforces what has been widely assumed: Many patients are using diabetes drugs off-label for weight loss, according to Sanjula Jain, Trilliant’s chief research officer.

“It’s a sizable share,” Jain said of estimated off-label use. “Not all patients taking these prescriptions are necessarily consulting a physician or medical professional for diabetes or obesity,” she added, pointing out that a large number of patients did not have traditional medical visits that coincided with a prescription.

The analysis is not the first to confirm the rise of the drugs, led by Ozempic, that have rapidly permeated popular culture and fueled a frenzy among patients and on Wall Street. A peer-reviewed study last year found that spending on semaglutide — the main ingredient in Ozempic and its weight-loss twin, Wegovy — was the fourth-highest among drugs nationally in 2021, increasing faster than for any other drug in the top 25. Both drugs are made by Danish drugmaker Novo Nordisk.

The new medications, often called GLP-1 drugs for the naturally occurring hormone they mimic, work by slowing the stomach from emptying and sending a signal of fullness to the brain. They have been found to help overweight people lose 15 to 20 percent of their body weight and reduce the risk of heart problems, but they also come with sometimes unpleasant side-effects such as nausea and vomiting. Nonetheless, the drugs are so much in demand that the manufacturers cannot produce enough, spawning an industry built around making cheaper imitations.

Inside the gold rush to sell cheaper imitations of Ozempic

That parallel industry is based in large part around the U.S. Food and Drug Administration’s determination that semaglutide and tirzepatide — the main ingredient in Mounjaro, another new diabetes drug often used for weight loss — are in shortage. This designation has opened the door for compounding pharmacies to mix up copies of the FDA-approved drugs and for a host of clinics and telehealth firms to market them.

It’s difficult to estimate the size of this parallel market, but Umer Raffat, an analyst for Evercore ISI, said in a research note last week that “there does appear to be meaningful volume flowing through these channels.”

It isn’t clear whether off-brand versions are counted in Trilliant’s analysis. The firm found that more than 9 million prescriptions were written in the last three months of 2022 for semaglutide, tirzepatide and liraglutide — an older GLP-1 drug that isn’t as effective as the other two for losing weight.

Trilliant also analyzed patient use of Ozempic in 15 big U.S. cities, which all posted an increase over a year, led by Cleveland, where usage shot up by 481 percent. Jain said the figures could be affected by many factors, from available supplies to health-insurance coverage.

“It would be difficult to pinpoint what exactly is driving the change,” she said.

The pharmaceutical industry is abuzz with companies racing to develop their own weight-loss drugs to compete with Ozempic, Wegovy and Mounjaro, from a new class of injectables to pill versions.

Analysts at Goldman Sachs on Tuesday published research highlighting 54 anti-obesity drugs in clinical trials or that have shown positive results in late-stage studies. Though uncertainties remain, they wrote, the new generation of weight-loss drugs has the potential to “become one of the largest therapeutic categories across the biopharmaceutical industry.”