What Do GLP-1 Medications Do: How They Work, Benefits, and Potential Risks

GLP-1 medications have been making headlines recently, particularly for their role in managing type 2 diabetes and weight loss.

Research published by University College London (UCL) in January 2026 estimated that 1.6 million adults in Great Britain had used medications, such as Mounjaro or Wegovy, to support weight loss in the previous year.

With more people turning to these medications, it’s increasingly important to understand how they work, the benefits they offer and the potential risks involved.

So, what do GLP-1 medications do, and are there any risks to be aware of?

In short, these medications, including well-known options like Mounjaro (tirzepatide), Ozempic (semaglutide), and others, work by mimicking a naturally occurring hormone in the body called GLP-1 (glucagon-like peptide-1). This helps regulate blood sugar levels, slow digestion, and reduce appetite.

GLP-1 medications can be effective for managing type 2 diabetes and supporting weight loss, but they can also cause side effects such as nausea, vomiting and constipation.

If you’ve been prescribed one of these medications or are considering them, here’s what you need to know.

How Do GLP-1 Medications Work?

GLP-1 medications work by activating receptors for GLP-1, a hormone naturally released by the gut after eating.

This helps the body control blood sugar levels, slows how quickly food leaves the stomach and reduces feelings of hunger, making these medications useful for managing type 2 diabetes and supporting weight loss.

Here’s an overview of how GLP-1 medications work in the body.

1. Enhancing Insulin Release: When you eat, GLP-1 medications stimulate the pancreas to release insulin, which helps lower blood sugar levels.
2. Reducing Glucagon: They reduce the amount of glucagon, a hormone that raises blood sugar levels, which is often overactive in people with type 2 diabetes.
3. Slowing Digestion: GLP-1 medications can slow gastric emptying, meaning food moves from the stomach into the small intestine more slowly. This can help you feel fuller for longer, potentially reducing appetite and supporting weight loss.
4. Acting on the Brain: GLP-1 drugs also act on brain areas that regulate hunger, leading to a decrease in appetite. One study found that participants taking semaglutide consumed 35% fewer calories during a test lunch than those taking a placebo.

Mounjaro: A New Generation GLP-1 Option

Earlier GLP-1 medications, such as Ozempic (semaglutide), were initially developed to manage type 2 diabetes. Their use increased significantly over time, with UK Parliament figures showing that NHS dispensing of Ozempic injections in England rose from 111,388 in 2019 to over 1.1 million in 2022.

Ozempic works by targeting GLP-1 receptors to help regulate blood sugar levels in people with type 2 diabetes. It can also support weight loss by reducing appetite, although it is not specifically licensed for weight management in the UK.

However, newer medications such as Mounjaro (tirzepatide) take a slightly different approach. Originally authorised for type 2 diabetes, Mounjaro was approved for weight management in the UK in November 2023, following clinical trials demonstrating its effectiveness in supporting weight loss.

Unlike Ozempic, Mounjaro targets both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors, which are involved in blood sugar control and appetite regulation.

This dual action can offer additional benefits. In fact, a 2021 clinical trial involving 1,879 people with type 2 diabetes found that Mounjaro achieved greater reductions in blood sugar levels and body weight than semaglutide at a 1 mg weekly dose over 40 weeks.

These findings suggest that Mounjaro may offer greater benefits for some patients seeking to manage both their blood sugar levels and weight, although individual results can vary.

What Are the Benefits of GLP-1 Medications?

GLP-1 medications offer several benefits, especially for people with type 2 diabetes, but their effects go beyond just managing blood sugar:

1. Improved Blood Sugar Control: GLP-1 medications can significantly lower HbA1c levels (a measure of average blood sugar over the previous two to three months), which can help people with type 2 diabetes manage their condition.
2. Weight Loss: Many people experience meaningful weight loss while on GLP-1 medications, with Mounjaro in particular showing more pronounced effects compared to earlier GLP-1 drugs.
3. Cardiovascular Benefits: Certain GLP-1 medications have been shown to reduce the risk of serious cardiovascular events, including heart attacks and strokes, in specific patient groups. This is particularly important for people with type 2 diabetes, who face an increased risk of cardiovascular disease.
4. Reduced Risk of Hypoglycaemia: GLP-1 medications don’t typically cause dangerously low blood sugar levels, a common concern with some other diabetes treatments like insulin or sulfonylureas. However, Diabetes UK explains that the risk can increase when they’re combined with insulin or sulphonylureas, making medical supervision important.

GLP-1 Medication: Risks and Side Effects

Like all medications, GLP-1 drugs can have side effects. Most are mild and improve over time, but it’s important to be aware of them:

1. Gastrointestinal Issues: Nausea, vomiting, diarrhoea, and constipation are common, particularly when starting the medication. These side effects are usually temporary.
2. Decreased Appetite: While reduced appetite can lead to weight loss, it might cause some individuals to eat less than recommended, leading to nutritional deficiencies if not monitored properly.
3. Injection Site Reactions: Since most GLP-1 medications are injectable, some people may experience mild redness or discomfort at the injection site.
4. Pancreatitis Risk: Though rare, there have been reports of GLP-1 medications being linked to an increased risk of pancreatitis (inflammation of the pancreas). The MHRA updated its safety guidance in January 2026, highlighting rare but potentially severe cases. Anyone experiencing persistent, severe abdominal pain should seek urgent medical attention.
5. Thyroid Cancer Concerns: In animal studies, GLP-1 medications have been associated with an increased risk of thyroid tumours. However, a 2024 study involving over 145,000 GLP-1 users found no substantial increase in thyroid cancer risk. Further research is needed to understand any potential long-term risks in humans.

Is GLP-1 Right for You?

GLP-1 medications may be suitable for people with type 2 diabetes or those living with obesity. Certain treatments, such as Mounjaro and Wegovy, are licensed for weight management in people who are overweight and have related health conditions.

However, eligibility depends on several factors, including your BMI, medical history and overall health. According to the NHS, Mounjaro may not be suitable for people with certain medical conditions, including a history of pancreatitis.

GLP-1 medications are also not recommended during pregnancy or when trying to conceive, as there is insufficient evidence about their safety.

Before starting treatment, it’s important to speak with a qualified healthcare professional who can assess your individual needs, explain the potential risks and determine whether GLP-1 medication is appropriate for you.

How Can We Help

GLP-1 medications, such as Mounjaro and Wegovy, can be effective tools for managing weight, but they’re not suitable for everyone. Understanding your treatment options and receiving the right medical support is essential for achieving safe, sustainable results.

At The Lagom Clinic, we take a personalised approach to weight management.

Our experienced doctors will assess your medical history, discuss your weight loss goals and recommend a treatment plan suited to your individual needs.

Check out our weight loss programme and book a consultation to find out which treatment is the best for you.