CagriSema pen usability: the study results

A new injectable obesity drug combining two active compounds in a single pen raises an obvious question: can patients actually use it correctly? A usability study published in the Journal of Diabetes Science and Technology on 28 June 2026 set out to answer that for the CagriSema autoinjector^[1]. CagriSema pairs cagrilintide, a long-acting amylin analogue, with semaglutide in a fixed-ratio combination delivered in one weekly subcutaneous injection.

What is in the pen

The device is a single-dose, single-use, pre-filled autoinjector. Each cartridge contains both cagrilintide and semaglutide at a 2.4 mg / 2.4 mg fixed dose, the same doses studied in the REDEFINE phase 3 programme^[2]. Novo Nordisk designed the dual-chamber format because the two compounds must be kept physically separate until the moment of injection to preserve stability. That architecture is more complex than a single-compound pen, which is exactly why a formal usability study matters.

Unlike an efficacy or safety trial, a usability study does not measure whether a drug works or causes side effects. It measures whether people can operate the device correctly after receiving standard training. The study population included 85 adults with overweight or obesity and 65 adults with type 2 diabetes, a total of 150 participants.

How the study worked

Participants performed simulated injections following standardised training. The primary outcomes were ease of use, ease of learning, and overall convenience, assessed by self-report after the simulated injection. Training time and injection time were also recorded. Researchers also collected data on whether the prior experience of each participant with self-injection devices affected how well they managed the CagriSema pen.

The median training time was 3 minutes. The median time to prepare and complete the injection was 15 seconds. Those numbers are relevant context: if training takes under 5 minutes and the injection takes 15 seconds, the device is not placing an unusual burden on the person using it, at least in a controlled simulation setting. By comparison, training for insulin pen use in clinical trials can take 10 to 20 minutes for device-naive participants.

What participants reported

The results were strongly positive across all three primary measures. All participants who completed the injection rated the device easy or very easy to use (100%). Of those, 98.7% found it easy or very easy to learn, and 99.3% considered the injection convenient^[1]. Only one participant did not complete the injection successfully.

Crucially, the results held across both participant groups (overweight/obesity and type 2 diabetes) and were not affected by whether participants had prior experience with injectable devices. This matters because clinical populations vary widely in device familiarity: someone who has injected insulin daily for years is very different from someone injecting a medication for the first time.

What this study does not tell us

A usability study conducted under standardised conditions is not the same as real-world device experience. Participants in clinical research settings are typically more carefully supported than most outpatients, and simulated injections take place without the anxiety or time pressure of everyday life. The study also does not address whether patients maintain correct technique over weeks and months of self-administration, or what happens when a dose is missed and a participant needs to recall the process from memory.

Regulators treat this kind of study as one layer of evidence in a broader device dossier, not as a stand-alone proof of real-world usability. Post-marketing device surveillance and patient support materials will ultimately shape how well injection success rates hold up outside a clinical protocol. These caveats are not unique to the CagriSema pen. They apply to any injectable combination product entering a new patient population.

The usability findings also say nothing about whether the drug combination works. The primary efficacy question is addressed in the REDEFINE clinical programme. REDEFINE 1 (3,417 adults with overweight or obesity) reported 20.4% mean body weight reduction with CagriSema versus 3.0% with placebo at 68 weeks. REDEFINE 2 studied adults with overweight or obesity and type 2 diabetes. Those are separate evidence questions from whether the pen itself is usable. For more on how semaglutide functions as a component of this combination, see the semaglutide overview.

Context for CagriSema's development

CagriSema is not yet approved in any major jurisdiction as of June 2026. The combination is in late-stage development at Novo Nordisk. The published usability data is part of the evidence package that would support regulatory submission, alongside efficacy and safety data from the REDEFINE trials. Device usability studies are a standard requirement from regulators including the FDA and EMA before an injectable combination product can be approved for prescription use. The FDA guidance on human factors engineering for combination products, for example, requires manufacturers to demonstrate that users can operate the device correctly without errors that could lead to harm.

The amylin component, cagrilintide, acts through a different mechanism than semaglutide. Amylin is a pancreatic hormone that signals satiety, slows gastric emptying, and suppresses glucagon. Semaglutide is a GLP-1 receptor agonist that also slows gastric emptying and reduces appetite through central and peripheral pathways. Combining them in a single injection means patients receive two complementary satiety signals without two separate injections, which is the pharmacological rationale behind the fixed-ratio pen format. The device study examined here is not about whether that pharmacology works. It is about whether the delivery mechanism is accessible to the people the drug is intended to reach.