GLP-1 receptor agonists (GLP-1 RAs or GLP-1s) are a type of medication you might need to take if you have type 2 diabetes. They are also known as GLP-1 analogues, GLP-1 agonists and incretin mimetics.
- What are GLP-1 medications?
- How do GLP-1s work?
- Different types of GLP-1 medications
- Who can take GLP-1s?
- Your prescription
- GLP-1 side effects
- More information and support
What are GLP-1 medications?
Glucagon-like peptide-1 (GLP-1) is a naturally occurring hormone in the gut and is released after eating. GLP-1 RAs are medications that mimic the action of natural GLP-1. They can be prescribed to lower blood sugar levels in people living with type 2 diabetes. They can also be prescribed to support people with weight loss or to reduce the risk of major cardiovascular events such as heart attack or stroke in people living with cardiovascular disease (CVD) and obesity or overweight.
How do GLP-1s work?
These medications work by increasing the levels of incretins – hormones – which help the body produce more insulin when needed and lower blood sugar levels.
Many people lose weight when they take a GLP-1 medication as part of their type 2 diabetes treatment. This is because these drugs slow down how quickly food is digested, make you full for longer and can reduce your appetite, so you eat less.
Different types of GLP-1 medications
There are many different GLP-1 containing medications that can be prescribed as a treatment for type 2 diabetes and weight management in the UK, they each have a generic (medical) name and one or more brand names. These include:
- Tirzepatide can be prescribed as a treatment for type 2 diabetes or weight management. It’s a dual GLP-1 and GIP receptor agonist which means it works in a similar way to a GLP-1 but also acts on another hormone called GIP (glucose-dependent insulinotropic polypeptide). It’s an injection that you give once a week. The brand name is Mounjaro.
- Semaglutide can be prescribed as a treatment for type 2 diabetes or weight management. For type 2 diabetes, semaglutide has the brand names Ozempic, an injection given once a week and Rybelsus a tablet taken once a day. Wegovy is the brand used for weight management, and it can also be prescribed to reduce CVD risk in people living with CVD and obesity or overweight.
- Dulaglutide can be prescribed as treatment for type 2 diabetes and has the brand name Trulicity; it is a once-weekly injection.
- Liraglutide can be prescribed as a treatment for type 2 diabetes or weight management. For type 2 diabetes, liraglutide has the brand names Diavic and Zegluxen. Saxenda, Biolide and Nevolat are the brands used for weight management. They are injections that are given once a day.
Although most GLP-1 medications are given via injection, they are different medications to insulin.
The GLP-1s listed are examples of those that are prescribed on the NHS, newer brands are continually being developed, so you may find that the one you’ve been prescribed is not listed on this page. If you have any concerns or questions about your medication, it’s important to speak to your healthcare team.
Who can take GLP-1s?
Type 2 diabetes
Adults aged 18 and over with type 2 diabetes can be prescribed GLP-1s for type 2 diabetes management.
As well as lowering blood glucose levels these medications can also help to protect the heart and kidneys. Not everyone with type 2 diabetes will need to take a GLP-1.
New guidelines from the National Institute for Health and Care Excellence, or NICE for short, recommend earlier use of these medications for some groups of people. You’re more likely to be offered a GLP-1 if you’re an adult with type 2 diabetes and:
- You were diagnosed before the age of 40
- Have cardiovascular disease such as heart disease or stroke
- Are living with obesity.
Your healthcare team will discuss your options to decide if this treatment is right for you based on your individual needs and circumstances. If you think that you would benefit from taking a GLP-1 medication - speak with your healthcare team so that you can make an informed decision together about your treatment.
NICE guidelines are used in England and Wales and tend to be endorsed and adopted in Northern Ireland. If you live in Scotland, care may be based on SIGN guidelines. Please speak to your healthcare team if you have any questions or concerns about your treatment.
Managing obesity and overweight
GLP-1 agonists can also be prescribed to manage obesity and overweight to adults, alongside a reduced-calorie diet and physical activity.
There are currently three GLP-1s used for managing obesity and overweight. These are semaglutide (Wegovy) and liraglutide (Saxenda, Biolide, Nevolat) which are usually prescribed within specialist weight management services and tirzepatide (Mounjaro) which can be prescribed by a GP.
You should only be given a prescription for a GLP-1 agonist following an assessment by your healthcare team to make sure that you meet the criteria and that you’ll benefit from it.
This should be an individual assessment that includes how this medication will fit into your current treatment plan and considers any diet or activity programme that you are following, as well as the risk of side effects, the dose you’ll need, and your personal preferences.
It is important that the healthcare professional prescribing your medication is aware of your full medical history, including type of diabetes, and accurate body weight.
Guidance has been produced for pharmacists providing private prescriptions.
Cardiovascular disease
The GLP-1 semaglutide (Wegovy) might be prescribed to adults living with cardiovascular disease and obesity or overweight to reduce the risk of major cardiovascular events such as heart attack or stroke. This includes people living with or without type 2 diabetes.
Can children take GLP-1 medications?
Dulaglutide and liraglutide are licensed to treat children and young people aged 10 and over with type 2 diabetes. NICE guidelines recommend they’re offered to children who meet certain eligibility criteria. Liraglutide and semaglutide are licensed for weight management in children and young people aged 12 and over who live with obesity and weigh over 60kg, they are usually only prescribed in specialist weight management clinics by specialist doctors.
Who can’t take GLP-1 medications?
Some medications might not be suitable for some people, which might be because of medical conditions or other reasons. The list below shows some of the reasons a GLP-1 agonist might not be a suitable treatment for you
- Certain GLP-1's might not be suitable for you if you have severe problems with your digestion. You might also need to temporarily stop taking your GLP-1 if you’re going to have an operation;
- If you have kidney disease, you might not be able to take a GLP-1, or your dose might need to be changed - this will depend on the stage of your kidney disease;
- If you have severe liver disease, you might also not be able to take this medication;
- If you’ve had pancreatitis before, a GLP-1 might not be suitable for you. Your doctor will tell you to stop taking this medication if you have pancreatitis.
- You should not take this medication if you are pregnant or breastfeeding. If you’re planning a pregnancy, speak with a healthcare professional if you are using this medication;
- Your doctor will tell you to stop taking your GLP-1 medication if you develop diabetic ketoacidosis, also called DKA.
The patient information leaflet that comes with the medication will have an up-to-date list of warnings and precautions. When you start a new medication, always check with your healthcare team that it’s suitable for you to take you can discuss any other medical conditions you have and any other medications you are taking.
Can I take a GLP-1 if I have type 1 diabetes?
GLP-1s are not licensed to treat type 1 diabetes. But some people use them “off label”, usually for weight management, under supervision from specialist doctors.
GLP-1s are not a replacement for insulin, and their use in type 1 diabetes is still being studied. If you have type 1 diabetes and are interested in GLP-1 medications, speak to your diabetes team. They can advise you on the latest evidence and give you personalised advice.
Your prescription
Your healthcare team should explain your prescription to you but it's important to make sure you ask if you don't feel you know enough.
And make sure you talk to your GP or your diabetes team if you struggle to take your medication. They might be able to help by giving you a different dose.
In England, if you need to take any medication to manage your diabetes, your prescriptions will be free. Ask your healthcare team about a prescription exemption certificate if you don't have one, to make sure you don't get charged for your medication. Prescriptions are already free for everybody in the rest of the UK, so you shouldn't pay for medication.
GLP-1 side effects
Common side effects can include:
- feeling sick (nausea)
- being sick (vomiting)
- constipation
- diarrhoea
- risk of low blood sugar
- risk of worsening retinopathy
Risk of low blood sugar
This medication does not usually cause blood sugar levels to become too low, also known as hypoglycaemia, or hypos, when taken on their own. But hypos can happen when you take GLP-1 agonists with other diabetes medications such as insulin or a sulphonylurea.
Your healthcare team may advise reducing the dose of your sulphonylurea or insulin medicine when you start taking a GLP-1 to reduce the risk of hypos.
Risk of high blood sugar
If you take a GLP-1 agonist with insulin and your insulin dose is reduced too quickly it can cause high blood sugar levels, this is also called hyperglycaemia, and there is an increased risk of DKA. Your health care team should discuss with you the signs and symptoms of DKA.
And you should have a plan for when you are unwell, which is also known as sick day rules.
Risk of worsening retinopathy
If you have diabetic eye disease, known as diabetic retinopathy, and you’re using insulin, then your retinopathy could get worse when you start using semaglutide, and this might need treatment.
Tell your doctor if you have diabetic eye disease or if you experience eye problems during treatment with semaglutide.
Risk of Non-arteritic anterior ischemic optic neuropathy (NAION)
NAION is a condition that affects the optic nerve in the eye. NAION happens when blood flow to the optic nerve is reduced. This can cause sudden loss of vision, typically in one eye. It’s often described as a blurring or cloudiness of vision. Semaglutide (Ozempic, Ry has been associated with very rare reports of NAION. If you notice a sudden change in your eyesight such as sudden vision loss or your eyesight gets worse very quickly in one or both of your eyes during treatment with semaglutide, seek urgent medical advice.
Risk of acute pancreatitis
Acute pancreatitis is a condition where the pancreas becomes inflamed (swollen) over a short period of time.
Although uncommon, there have been reports of acute pancreatitis in people taking GLP-1 medications. While it is infrequent, it can be serious. The main symptom is severe pain your stomach that radiates to your back. Other possible symptoms include:
- feeling or being sick (vomiting)
- Indigestion
- a high temperature of 38C or more (fever)
- yellowing of the whites of the eyes, and yellowing of the skin although this may be less obvious on brown or black skin
- tenderness or swelling of the tummy
- fast heartbeat (tachycardia) or rapid breathing.
If you experience any of these symptoms, it is very important to get urgent medical help.
These are not all the side effects. You will find a full list of known side effects in the Patient Information Leaflet. This comes in the medication box.
Like all medications, GLP-1 agonists can cause side effects. But when side effects are listed as common in the Patient Information Leaflet, it doesn’t mean that everyone who takes the medication will get them.
The information about side effects is based on the likelihood of people having them. For example, if a side effect is very common, then it can affect more than one in ten people, and if a side effect is very rare, then it affects fewer than one in 10,000 people.
Because medicines can affect people differently, your healthcare team will speak to you about what’s best for you and discuss any side effects.
It's important that you take individual advice from your healthcare team before starting treatment with GLP-1 agonist medication and report any side effects to your healthcare professionals, if you have any.
You can also report any side effects to the Yellow Card Scheme, which is the government system used for recording adverse effects and incidents with medicines in the UK.
Increased risk of suicidal thoughts
You may have heard in the news about a possible increased risk of suicidal thoughts and thoughts of self-harm when taking some GLP-1 agonists.
The European Medicines Agency (EMA) and the American Food and Drug Administration (FDA) have been investigating this. Their initial investigations have found that there was no evidence that taking these medicines causes suicidal thoughts or actions.
Thoughts and actions can be affected by many things in life so the findings were that the information in these reported events did not demonstrate a clear relationship with the use of GLP-1 agonists. But because of the small number of these events in people using GLP-1 agonists, they can’t completely rule out that a small risk may exist, so they are continuing to monitor the issue.
If you are taking a GLP-1, you should pay attention to any sudden changes in your mood, behaviours, thoughts and feelings and contact your healthcare team straight away if you are concerned about your mental health, especially if you have any new or worsening symptoms.
If you think these mood changes are a result of taking GLP-1, you can report this to the Yellow Card Scheme.
More information and support
If you're worried about your medication, struggling with side effects, or want to know if it's right for you, speak with your healthcare team.
Still have more questions? Or is there anything you're not sure about GLP-1 agonists after reading this page? Contact our helpline on 0345 123 2399.
You can visit the NHS website for more information.
