Endocrine / Diabetes
GLP-1 receptor agonists
e.g. semaglutide, liraglutide — Injectable (and some oral) diabetes drugs that lower glucose and support weight loss.
Education and reference only. This is a plain-language class overview — it deliberately contains no doses. Always check the current Summary of Product Characteristics (SmPC), the BNF and your local formulary before prescribing or administering any medicine.
What it is
GLP-1 receptor agonists are used in type 2 diabetes and, in specific licensed products, for weight management. Most are injectable, with some oral options.
How it works
They mimic the gut hormone GLP-1, which boosts insulin release when glucose is high, suppresses excess glucagon, slows stomach emptying and reduces appetite — lowering glucose and supporting weight loss.
In practice
In practice GLP-1 agonists lower glucose with a low risk of hypos on their own and produce meaningful weight loss, which is why interest has grown well beyond diabetes. Nausea is the commonest issue and is reduced by slow dose escalation. They are not a substitute for insulin in type 1 diabetes, and the licensed product and indication must be matched carefully, as weight-management and diabetes products differ.
Examples
Practical use
How to take it & use it well
- Most GLP-1 medicines such as semaglutide or liraglutide are given as an injection under the skin of the stomach, thigh or upper arm, on a regular schedule; an oral form of semaglutide is also available.
- Injectable doses are usually started low and increased gradually to reduce nausea, so follow the step-up plan your team gives you.
- Oral semaglutide must be taken on an empty stomach with a small sip of water, then wait before eating, drinking or taking other medicines.
- Rotate injection sites to avoid skin lumps or soreness in one spot.
- If you miss a dose, follow the specific instructions for your product, as the rules differ between weekly and daily versions; ask your pharmacist if unsure.
- Store injectable pens as directed, often in the fridge before first use, and avoid freezing them.
Common uses
- Type 2 diabetes
- Weight management (specific licensed products only)
Monitoring
- HbA1c and weight where relevant
- Tolerability during dose escalation
- Renal function if significant vomiting occurs
Weighing it up
Advantages & disadvantages
Advantages
- They lower blood sugar in type 2 diabetes and usually cause meaningful weight loss.
- Some have been shown to reduce the risk of heart problems in people at higher risk.
- On their own they have a low risk of causing low blood sugar.
- Weekly options mean some only need one injection a week.
- They help reduce appetite, which supports weight management.
Disadvantages
- Nausea, vomiting, diarrhoea and constipation are common, especially when starting or increasing the dose.
- Most versions are injections, which some people find off-putting.
- They can rarely cause inflammation of the pancreas, so severe ongoing stomach pain needs urgent assessment.
- The oral form has strict timing rules that must be followed for it to work.
- They are not suitable for everyone, including some people with certain stomach or thyroid conditions.
Key safety principles
What to watch for
- Nausea and gastrointestinal upset are common; escalate the dose slowly.
- Not for type 1 diabetes and not a replacement for insulin.
- Caution with a history of pancreatitis; match the exact product to the licensed indication.
Key interactions
What to avoid or check alongside
- Combined with insulin or sulfonylureas, the risk of low blood sugar from those medicines increases and doses may need adjusting.
- Because they slow stomach emptying, they can affect how quickly other tablets are absorbed.
- Oral semaglutide must be separated from food and other medicines, or its absorption drops.
- Heavy alcohol use can worsen stomach side effects and is best limited.
- Tell your team about any history of pancreas or gallbladder problems before starting.
Patient & carer advice
- Nausea usually eases over a few weeks — eat smaller meals
- Use the correct device and injection technique for your product
- These work best alongside diet and activity changes
Use with
Related clinical calculators
Dose and risk decisions for this class often depend on renal function, weight or bleeding/stroke risk. These tools help:
Answers
GLP-1 receptor agonists: frequently asked questions
Is this an insulin injection?
No. GLP-1 medicines are a different type of treatment. They help your body manage sugar and reduce appetite, and unlike insulin they rarely cause low blood sugar on their own.
Why do I feel sick when I start?
Nausea is common early on because these medicines slow the stomach. It usually eases as your body adjusts, which is why doses are increased slowly.
Can I take it as a tablet instead of an injection?
One form of semaglutide comes as a daily tablet with strict timing rules. Most other GLP-1 medicines are injections, so discuss the options with your prescriber.
Will it help me lose weight?
Yes, weight loss is common because the medicine reduces appetite and slows digestion, though the amount varies between people.
What if I miss my weekly injection?
The rules depend on how many days have passed and which product you use. Check your specific leaflet or ask your pharmacist rather than guessing.
Authoritative sources
Always verify against the source
This overview is for orientation. For doses, interactions, contra-indications and the full monograph, use:
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