What are GLP-1 medications and how do they work
Medically reviewed by Dr Sultan Linjawi, Endocrinologist & Diabetes Specialist — January 2026
GLP-1 medications have become some of the most talked-about treatments in type 2 diabetes — and for good reason. These medicines can improve blood sugar control, support weight loss, and in some cases reduce the risk of heart attack and stroke. However, with so many names now in circulation — Ozempic, Trulicity, Mounjaro, Rybelsus, Victoza, Xultophy — it can be difficult to understand what they actually do and how they differ.
In this guide, I’ll explain GLP-1 medications in clear, practical terms: how they work, why they are prescribed, what benefits and risks matter most, and how the different options compare. This is written for people with type 2 diabetes (and those with prediabetes or insulin resistance) who want to understand their treatment options properly — without hype or confusion.
What are GLP-1 medications?
GLP-1 stands for glucagon-like peptide-1, a hormone that your body naturally releases from the gut after you eat. Its job is to help keep blood glucose levels within a healthy range.
GLP-1 medications mimic this natural hormone, but in a longer-acting and more reliable way. They work through several important mechanisms:
- They increase insulin release from the pancreas when blood glucose is high
- They reduce excess glucose release from the liver
- They slow stomach emptying, helping prevent sharp glucose spikes after meals
- They increase feelings of fullness, often reducing appetite
Because these effects depend on blood glucose levels, GLP-1 medications on their own carry a very low risk of causing low blood sugar (hypoglycaemia).
Why are GLP-1 drugs used in type 2 diabetes?
Type 2 diabetes is driven by a combination of insulin resistance, reduced insulin production over time, and excess glucose output from the liver. GLP-1 medications target several of these problems at once.
They are now commonly used when:
- Metformin alone is no longer enough
- Weight gain is contributing to worsening glucose control
- There is a need to minimise hypoglycaemia risk
- Someone has existing cardiovascular disease or multiple risk factors
For many people, GLP-1 therapy can delay or reduce the need for insulin, or allow insulin doses to be kept lower and safer.
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Key benefits of GLP-1 therapy
The benefits of GLP-1 medications go beyond simply “lowering sugar numbers”.
Improved HbA1c: GLP-1 drugs consistently reduce HbA1c — an important long-term marker of diabetes control — often by 1–1.5%, depending on the agent and dose.
Low hypoglycaemia risk: Because GLP-1 medications only stimulate insulin release when glucose levels are elevated, the risk of low blood sugar is low unless they are combined with insulin or sulfonylurea medications.
Weight reduction: Many people experience meaningful weight loss, largely due to reduced appetite and earlier satiety. This weight loss itself further improves insulin sensitivity and metabolic health.
Cardiovascular protection:
Some GLP-1 medications have been shown to reduce the risk of major cardiovascular events — such as heart attack, stroke, and cardiovascular death — in people with type 2 diabetes, particularly those with existing cardiovascular disease or multiple risk factors.
These benefits have been demonstrated in large, well-designed cardiovascular outcome trials, including:
- Liraglutide (Victoza) – the LEADER trial , which showed a significant reduction in cardiovascular death and all-cause mortality
- Semaglutide (Ozempic) – the SUSTAIN-6 trial , demonstrating fewer major adverse cardiovascular events, particularly stroke
- Dulaglutide (Trulicity) – the REWIND trial , which showed a significant reduction in major cardiovascular events even in people without established cardiovascular disease
- Tirzepatide (Mounjaro) – cardiovascular outcome data from the SURPASS-CVOT programme are emerging, with early results suggesting cardiovascular benefit compared with insulin therapy
These cardiovascular effects are a key reason why GLP-1–based therapies are now recommended earlier in the treatment pathway for people with type 2 diabetes who have established heart disease or are at high cardiovascular risk.
GLP-1 medications for weight loss (with and without diabetes)
While GLP-1 medications were originally developed to treat type 2 diabetes, it has become clear that their effects on appetite regulation and satiety can lead to substantial weight loss — even in people who do not have diabetes.
GLP-1 hormones act on appetite centres in the brain and slow the rate at which food leaves the stomach. Together, these effects help people feel full sooner, stay full for longer, and reduce overall calorie intake without the constant sense of hunger that undermines many weight-loss attempts.
Because excess weight is closely linked to insulin resistance, fatty liver disease, sleep apnoea, cardiovascular disease, and progression to type 2 diabetes, weight loss achieved with GLP-1 therapy can have wide-ranging metabolic benefits — even before diabetes develops.
GLP-1 medications approved specifically for weight loss
Some GLP-1–based medications are approved specifically for chronic weight management in people who do not have diabetes but meet certain weight or health criteria.
- Saxenda – a higher-dose daily liraglutide formulation
- Wegovy – a higher-dose weekly semaglutide formulation
- Zepbound – the weight-loss formulation of tirzepatide
These medications are typically approved for adults with obesity, or for those who are overweight with additional health conditions such as high blood pressure, abnormal cholesterol, or sleep apnoea.
How does weight loss differ with and without diabetes?
People without diabetes often experience slightly greater weight loss than those with type 2 diabetes. This is likely because insulin resistance, insulin use, and long-standing metabolic disease can blunt weight-loss responses.
That said, weight loss in people with diabetes is still clinically meaningful and often leads to:
- Improved glucose control
- Reduced medication requirements
- Lower cardiovascular risk
- Better energy levels and mobility
Important considerations
GLP-1 medications are not cosmetic weight-loss drugs. They are prescription therapies intended for people with medical indications for weight reduction and should always be used as part of a structured, supervised plan.
Stopping GLP-1 therapy often leads to weight regain unless long-term lifestyle changes are maintained. For this reason, discussions around expectations, duration of therapy, and sustainability are essential before starting treatment.
Types of GLP-1 medications
GLP-1 therapies are available in several different forms:
Once-weekly injections
Daily oral or injectable options
Combination therapy with insulins
- Xultophy (insulin degludec + liraglutide)
- IcoSema (weekly insulin Icodec + Semaglutide)
- Soliqua (insulin glargine and lixisenatide)
How the main GLP-1 drugs compare
While all GLP-1 medications work through similar mechanisms, they differ in strength, dosing frequency, weight loss effects, and side-effect profiles. Newer agents tend to produce greater glucose lowering and weight loss, but may also cause more gastrointestinal symptoms during dose escalation.
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Side effects and safety considerations
The most common side effects of GLP-1 medications are gastrointestinal and include nausea, vomiting, diarrhoea, constipation, and abdominal discomfort. These effects are usually dose-related and often improve over several weeks.
Rare but important considerations include pancreatitis and gallbladder disease. GLP-1 therapies are not recommended in people with a personal or family history of medullary thyroid cancer or Multiple Endocrine Neoplasia type 2 (MEN2).
Who are GLP-1 medications suitable for?
GLP-1 therapies are approved for adults with type 2 diabetes and are not used in type 1 diabetes. They are also not recommended during pregnancy.
They are particularly useful for people who:
- Have type 2 diabetes with excess weight
- Struggle with hypoglycaemia on other therapies
- Have established cardiovascular disease
- Want to delay or minimise insulin use
Frequently Asked Questions
What does GLP-1 stand for?
GLP-1 stands for glucagon-like peptide-1. It is a hormone released from the small intestine after eating and plays an important role in regulating blood glucose, insulin release, appetite, and digestion.
Are GLP-1 medications the same as insulin?
No. GLP-1 medications are not insulin. They are hormone-like drugs that help your own pancreas release insulin in a more natural, glucose-dependent way and also reduce excess sugar from the liver and help you feel full sooner. Some combination products, such as Xultophy, contain both a long-acting insulin and a GLP-1 in the same pen.
Can GLP-1 medications be used in type 1 diabetes?
GLP-1 medications are not approved as a replacement for insulin in type 1 diabetes. In a few specialised situations a diabetes specialist may consider adding them to insulin in carefully selected people, but this is off-label and needs close monitoring. If you have type 1 diabetes, never stop or reduce your insulin on your own because you’ve started a GLP-1.
Will I definitely lose weight on a GLP-1 medication?
Many people do lose weight, but not everyone. Average weight loss in studies is helpful for understanding trends, but individuals vary. Some people lose a lot, some a little, and some not at all. Results tend to be better when the medication is combined with support for eating patterns, activity and sleep.
How long can I stay on a GLP-1 medication?
There is no fixed time limit. In trials and real-world experience, people have used GLP-1 medications safely for many years. In practice, we continue as long as the medicine is helping your glucose levels, weight and overall health, and as long as side effects are manageable and it remains affordable and available.
What happens if I stop taking a GLP-1?
If you stop suddenly, it is common for appetite to increase again and, over time, for some or all of the lost weight to return, especially without a solid plan in place. Blood glucose levels usually drift back towards where they were before treatment. If you are considering stopping, talk with your doctor so that any insulin or tablets can be adjusted safely.
Do I need to change my diet if I start a GLP-1 medication?
A GLP-1 can make it easier to eat less, but it doesn’t decide which foods you choose. You’ll get the best results if you use that “appetite window” to shift towards higher-fibre, lower-glycaemic-index foods, more vegetables and lean protein, and fewer sugary drinks and refined carbohydrates. This is something we cover in detail in our programs and webinars.
Can I drink alcohol while on a GLP-1?
Moderate alcohol is usually allowed, but there are some cautions. Alcohol itself can cause low blood sugar when combined with insulin or sulfonylureas, and it can irritate the stomach and pancreas. If you drink, keep within recommended limits, avoid binge drinking and discuss your individual situation with your healthcare team.
Do GLP-1 medications cause cancer?
Current human studies have not shown an increased overall cancer risk with GLP-1 medications. Because of rare thyroid tumours seen in animal studies, these drugs are avoided in people with a history of medullary thyroid carcinoma or MEN2. If you have concerns about cancer risk, talk them through with your doctor – it’s a very reasonable question to ask.
Are GLP-1 medications safe in pregnancy or breastfeeding?
No. GLP-1 medications are not recommended in pregnancy or during breastfeeding. If you are planning a pregnancy, you’ll usually be advised to stop these medicines some time before conception and switch to treatments known to be safe in pregnancy, such as insulin. Always discuss pregnancy plans with your diabetes team before making any changes.
What if I can’t access a GLP-1 because of cost or shortages?
Unfortunately, supply and funding issues are common. If a GLP-1 is not available or not affordable for you, there are still many other effective tools for improving your diabetes control and weight. These include SGLT2 inhibitors, optimised insulin regimens, structured education programs and targeted lifestyle support. Your doctor can help you build a plan that works with the options you actually have.
