Peptide basics

Who actually takes GLP-1 drugs, and who was actually studied

This page contains no dose, schedule or route, and does not tell you whether anything is appropriate for you. It sets a survey of self-reported use beside the enrolment records of the trials, and keeps the two clearly labelled.

What the survey measured

KFF's May 2024 Health Tracking Poll surveyed a nationally representative sample of 1,479 US adults between 23 April and 1 May 2024. It found that 12% said they had ever taken a GLP-1 agonist, including 6% who said they were currently taking one.¹

The margin of sampling error was about 3 percentage points overall. For the 189 respondents who said they had ever used one — the group most of the interesting sub-figures come from — it was about 9 points.¹

Reported use rose sharply among people with a relevant diagnosis: 43% among adults told by a doctor they have diabetes, 26% among those told they have heart disease, and 22% among those told in the past five years that they are overweight or obese.¹

Where the survey and the trials disagree

On gender, they disagree flatly. KFF reported that similar shares of adults took these drugs regardless of gender. STEP 1 randomised 1,453 women and 508 men, and SURMOUNT-1 randomised 1,714 women and 825 men.¹²³

On age, they disagree by more than a decade. Reported use was highest among adults aged 50 to 64, at about 19%. STEP 1's posted mean age was 46 and SURMOUNT-1's was 44.9.¹²³

On purpose, they disagree too. Among people who had taken one, 62% said it was at least in part to treat a chronic condition such as diabetes or heart disease, while fewer said they had taken it only to lose weight. The pivotal obesity trials excluded people with diabetes.¹²³

• Gender: similar shares across genders in the survey; roughly three-quarters female in the pivotal obesity trials.
• Age: highest reported use at 50-64; trial mean ages in the mid-forties.
• Indication: most reported use involved a chronic condition; the obesity trials excluded diabetes.
• Older adults: 8% of adults 65 and over reported use for a chronic condition, 1% for weight loss only.¹²³

Why the gap exists

Part of it is eligibility. The obesity trials excluded diabetes, which is the condition most commonly cited by people reporting use, so the people most likely to be taking one of these drugs were structurally absent from the weight-management evidence.¹²

Part of it is that trials recruit rather than sample. FDA guidance to sponsors on eligibility criteria and enrolment practices exists precisely because trial populations tend not to reflect the populations that eventually use a product, and recommends approaches to narrow that gap.⁶

Part of it is which trial you look at. The same compound's cardiovascular outcomes trial enrolled 17,604 adults at a mean age of 61.6 years and was 72.3% male, which is much closer to the reported user profile — but it studied cardiovascular endpoints in people with established cardiovascular disease, not weight management.⁴

And part of it is coverage. KFF noted that Medicare is currently prohibited by law from covering prescription drugs used for weight loss, which they suggested may explain why only 1% of adults 65 and over reported taking one for weight loss alone.¹

What that means for reading a number

It means a headline figure from a pivotal trial should be read with its population attached, and that the population is not the general public. The approved US labeling reflects this by describing what was studied rather than generalising it.⁵

It also means the reverse error is worth watching for. A survey showing broad, gender-balanced use is not evidence that the trial results generalise; it is evidence that the drugs are being used by people the trials did not enrol.¹²

The KFF figure covers GLP-1 agonists as a class. It is not a prevalence figure for semaglutide, or for any single molecule, and should not be quoted as one.

Common questions