AuthorisedTherapeutic use (Phase IV)Interventional

Do GLP-1 based therapies improve the immunological response to vaccination in diabetes?

People with diabetes have a higher risk of developing serious chest infections, such as pneumonia. Vaccines help protect against these illnesses, but the body's immune response can sometimes be weaker in people with diabetes. This study tests whether a widely used diabetes injection called Victoza (liraglutide) can help the body respond better to the Pneumovax 23 vaccine. Victoza belongs to a group of medicines called GLP-1 treatments, which help control blood sugar and may also support healthy immune defences. Researchers will give participants the pneumonia vaccine and measure antibody levels in their blood after one and four months. They will also look at markers of inflammation and check for any side effects. The aim is to find out whether this treatment can help people with diabetes get better, longer-lasting protection from routine vaccinations.

At a glance

Status

Authorised

Phase

Therapeutic use (Phase IV)

Sponsor

Radboud universitair medisch centrum Stichting

Enrolment target

100

Start

22 Jul 2026

Diabetes

What is this study about?

Living with diabetes can make it harder for the body to fight off infections. Pneumonia is a serious lung infection caused by bacteria, and people with diabetes are more likely to become unwell if they catch it. While vaccines like Pneumovax 23 are routinely offered to protect against these bacteria, the immune systems of people with diabetes do not always produce as many protective antibodies as hoped.

Victoza is an approved medicine that many people already take to manage type 2 diabetes. It belongs to a family of drugs known as GLP-1 receptor agonists. Aside from lowering blood sugar levels, scientists believe these medicines may also reduce inflammation and help immune cells do their job better. This trial aims to see if taking this medicine gives the immune system an extra boost when receiving a pneumonia jab.

During the trial, doctors will track how many antibodies participants produce over four months. Antibodies are special proteins made by the immune system to remember and destroy germs. By checking blood samples, the research team can see whether the medication leads to a stronger shield against infection.

If the results are positive, this study could change how doctors protect people with diabetes from dangerous illnesses. It may show that standard diabetes treatments can double up as tools to make life-saving vaccines work even better.

Key takeaways

Tests whether the diabetes medicine Victoza improves protection from the pneumonia jab.
Open to adults aged 18 and older who have diabetes.
Involves receiving a vaccine and attending follow-up visits over four months.
Blood tests will check antibody levels at one month and four months.
Participation is voluntary and will not affect your standard NHS care.

Who may be eligible?

This study is open to adults aged 18 and over who have been diagnosed with diabetes. Both men and women can take part. Because this is a Phase IV trial, the treatments being used are already approved and well-understood by doctors.

To join, you must be able to attend regular check-ups and give blood samples across the four months of the study. The study team will review your medical history to ensure that taking part is safe for you.

You might not be able to take part if you have recently received a pneumonia vaccine, have severe allergies to any ingredients in the injections, or have certain other medical conditions that could interfere with the study results. Your doctor or the research team will help confirm if you qualify.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged 18 or older.
I have been diagnosed with diabetes.
I am willing to receive the pneumonia vaccine.
I can attend clinic visits over a four-month period.
I am happy to give blood samples for research.

Answer every question to see your result.

What does participation involve?

Taking part in this study lasts around four months. At the start, you will receive the Pneumovax 23 vaccine, which is given as a single injection into your upper arm, along with guidance on your diabetes medication. You will need to attend hospital or clinic visits at the beginning, at one month, and at four months.

At these visits, the research team will take routine blood samples to measure your antibody levels and check for signs of inflammation. You will also be asked to complete short questionnaires to report any mild side effects, such as a sore arm or fever. The team will keep in touch to check on your general health and see whether you have experienced any infections.

Potential risks and benefits

A potential benefit of joining is receiving a vaccine that protects against pneumonia, along with extra health checks from medical specialists. However, you might not receive a direct medical benefit from the trial itself. The risks are generally low and similar to routine care. The pneumonia jab can cause temporary redness, swelling, or soreness in the arm, as well as mild flu-like symptoms. Victoza can sometimes cause mild stomach upset or nausea when first used. Taking part is completely voluntary, and you are free to leave the study at any point without it affecting your standard NHS care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Netherlands

Common questions

What is the Pneumovax 23 vaccine?

It is a standard vaccine that protects against 23 common types of bacteria that cause pneumonia, blood poisoning, and meningitis.

What is Victoza?

Victoza is an established prescription injection for diabetes that helps manage blood sugar and may also help calm inflammation in the body.

Will taking part cost me anything?

No, the study medication, vaccines, and tests are provided free of charge, and trial sites often help cover reasonable travel costs.

Do I have to stop taking my regular diabetes medicines?

No, you should never stop your routine medicines unless the study doctor specifically advises you to do so after reviewing your health.

What happens if I change my mind?

You can leave the study at any time. Your normal medical care will continue as usual, and you do not have to give a reason.