GLP-1 agonists

GLP-1 agonists 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 RAs and incretin mimetics.

• What are GLP-1 agonists? 
• Supply issues of GLP-1 agonists 
• How do GLP-1 agonists work? 
• Different types of GLP-1 agonists 
• Who can take GLP-1 agonists?
• Your prescription 
• GLP-1 agonists side effects 
• More information and support

Avoid buying GLP-1 agonists online. These medications should be prescribed and monitored by a healthcare professional. Read our FAQs on GLP-1 agonist shortages for more information.

What are GLP-1 agonists? 

These drugs can be prescribed to lower blood sugar levels in people living with type 2 diabetes. They can also be prescribed to support some people with weight loss. 

Supply issues of GLP-1 agonists 

The NHS has been facing supply issues with GLP-1 agonists, which could impact your treatment.  

We are very concerned about these shortages. You can read our response to the serious supply issues of drugs for people with type 2 diabetes to learn more about how your treatment could be affected. You can also read our FAQs on GLP-1 shortages. 

Your healthcare team should get in touch if these shortages will affect you, but you can contact them if you're worried or have questions. Give our helpline a call if you have questions or concerns – call 0345 123 2399. 

How do GLP-1 agonists work? 

This medication works by increasing the levels of incretins – hormones – which help the body produce more insulin when needed and lowers blood sugar levels.

GLP-1 agonists and weight loss 

Some people lose weight when they take a GLP-1 agonist as part of their type 2 diabetes treatment. This is because these drugs slow down how quickly food is digested and can reduce your appetite, so you eat less.  

Different types of GLP-1 agonists 

There are many GLP-1 agonists that can be prescribed to people living with type 2 diabetes in the UK, which have a variety of brand names.  

Semaglutide 

Semaglutide is available under three different brand names:  

• Ozempic – a type 2 diabetes medication that you inject, which is prescribed to manage blood glucose levels. It should only be prescribed to people with type 2 diabetes. 
• Rybelsus – a drug that comes as a tablet that you swallow, which can be used to treat type 2 diabetes. 
• Wegovy – a drug that you inject, which is available on the NHS to support weight management. 

Exenatide 

Exenatide is injected once a week. It has the brand name Bydureon.  

Exenatide used to have the brand name Byetta, which was injected twice a day. Byetta was discontinued in March 2024.  

In January 2024, a National Patient Safety Alert was issued by NHS England and the Department for Health and Social Care to address supply issues with GLP-1 agonist medication.

The new alert directs healthcare professionals to identify people who have been prescribed Byetta injections and, in line with guidelines from the National Institute of Health and Care Excellence, or NICE for short, switch them to Rybelsus tablets by 28 March 2024.   

You should contact your healthcare team if you’re affected by shortages of GLP-1 agonists or if you have questions about your treatment with Byetta. 

There are other types of GLP-1 agonists used to treat type 2 diabetes, which you inject once a week: 

• Victoza, a brand name for liraglutide 
• Lyxumia, the brand name for lixisenatide  
• Trulicity, the brand name for dulaglutide. 

There is another medication called Mounjaro which sits in a different drug class, but it also works like a GLP-1 agonist to produce more insulin when needed and lower blood sugar levels

Who can take GLP-1 agonists? 

Adults over the age of 18 with type 2 diabetes can take GLP-1 agonists. 

Children over the age of 10 with type 2 diabetes can take two GLP-1 agonists: Victoza and Bydureon. 

Guidelines from NICE recommend that adults with type 2 diabetes can be prescribed a GLP-1 agonist if they: 

• Have previously used three diabetes medications and this has not helped to manage their type 2 diabetes; 
• Have not been able to take medications – this might be because of side effects or because of other medical conditions.  

BMI guidelines 

GLP-1 agonists are only prescribed when someone has a Body Mass Index, or BMI, of 35kg/m2 or higher, and has additional psychological or other medical conditions that are related to obesity.   

However, someone with type 2 diabetes can be prescribed a GLP-1 agonist if they have a BMI below 35kg/m2 and: 

• Using insulin would affect their job due to the risk of hypoglycemia; 
• Weight loss would lead to improvements in other obesity-related health issues. 

NICE recommends – due to their risk from obesity-related health problems at a lower BMI – that people from Black African, African-Caribbean, Asian, South Asian, Chinese, and Middle Eastern backgrounds receive treatment with GLP-1 agonist at a lower BMI.  

Managing overweight and obesity 

Adults over 18 years might be prescribed a GLP-1 agonist for managing overweight and obesity alongside a reduced-calorie diet and physical activity.  

There are two GLP-1 agonists that can be used for managing overweight and obesity. One is called Wegovy and the other is called Saxenda.

Adults with prediabetes or type 2 diabetes can only be prescribed Wegovy and Saxenda within specialist weight management services. 

Mounjaro has also been recommended to treat obesity on the NHS. Under draft NICE guidelines, a Mounjaro prescription could be stopped if someone’s weight loss is less 5% after six months. There would be no time limit for how long someone could take Mounjaro, and – unlike Wegovy and Saxenda – there is no stipulation that it has to be delivered in specialist weight management services.  

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 choices. 

Who can’t take GLP-1 agonists? 

Some medications might not be suitable for some people, which might be because of medical conditions or other reasons:   

• Your doctor will tell you to stop taking your GLP-1 medication if you develop diabetic ketoacidosis, also called DKA; 
• You might not be able to use certain GLP-1's if you have severe problems with your digestion. You might also need to temporarily stop taking your GLP-1 agonist if you’re going to have an operation; 
• If you have kidney disease you might not be able to take a GLP-1 agonist, 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;
• You should not take this medication if you are pregnant of breastfeeding. If you’re planning a pregnancy, speak with a healthcare professional if you are using this medication.

When you start a new medication always check with your healthcare team that it’s suitable for you to take. 

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 agonists side effects 

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.  

Common side effects can include: 

• nausea 
• constipation  
• diarrhoea. 

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 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 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. 

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.   

It's important that you take individual advice from your healthcare team before starting treatment with this medication and report any side effects to your healthcare professionals, if you have any.  

You can also report these side effects to the Yellow Card Scheme, which is the government system used for recording side effects with medicines in the UK. 

More information and support 

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.