Effect of semaglutide added to sulfonylurea on blood sugar in adults with HNF1A‑MODY and HNF4A‑MODY

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What is this study about?

The study looks at two rare forms of early‑onset diabetes called Maturity-onset diabetes of the young type 3 (HNF1A-MODY) and Maturity-onset diabetes of the young type 1 (HNF4A-MODY). These conditions are caused by changes in specific genes and lead to high blood sugar from a young age. Participants will continue taking their usual oral medicine called sulfonylurea, which helps the pancreas release insulin, and will receive either the injectable medicine semaglutide once a week or a matching placebo. The purpose of the study is to see how much the weekly injection can lower blood sugar when added to the existing treatment.

The trial lasts several weeks, starting with a short period where the dose of the injection is gradually increased, followed by a maintenance phase where the dose stays the same. During the last two weeks of each treatment period, participants will wear a small sensor that continuously records glucose levels, known as a CGM, and will also have routine blood tests such as the average sugar level test called HbA1c. The study compares the results from the weeks when the active injection is used with the weeks when the placebo is used to determine any differences in blood sugar control and related measurements.

1 initial visit and baseline assessments

you will attend an appointment where the study team will confirm that you meet the eligibility criteria for the trial.

you will provide informed consent, allowing the collection of health information and blood samples.

baseline measurements will be taken, including blood pressure, weight, height, waist circumference, and a blood draw to measure HbA1c, fasting plasma glucose, and fasting plasma C‑peptide (a marker of insulin production).

a continuous glucose monitor (CGM) sensor will be placed on your abdomen to record glucose levels continuously for the first two weeks of each treatment period.

2 start of first treatment period (semaglutide or placebo)

you will receive a weekly subcutaneous injection (injection under the skin) of either semaglutide 0.5 mg or a matching placebo 0.37 ml, depending on the random assignment.

the first injection will be given at the clinic, and you will be taught how to administer the injection yourself at home for subsequent weeks.

3 dose titration phase (first 10 weeks)

during the first ten weeks you will start with a lower dose of semaglutide (0.25 mg) if you are assigned to the active drug, and increase to the full dose of 0.5 mg after one week, provided you do not experience significant side effects.

the placebo will be given in the same volume each week (0.37 ml) without dose changes.

you will continue the weekly injections at the same day each week and keep a simple diary of any symptoms or adverse events.

4 maintenance phase (weeks 11–16)

for the remaining six weeks of the treatment period you will maintain the same weekly dose: 0.5 mg of semaglutide or the fixed volume of placebo.

you will continue to record any side effects and keep the injection schedule consistent.

5 continuous glucose monitoring (last two weeks of each period)

during the final two weeks of the 16‑week treatment period you will wear the continuous glucose monitor continuously.

the sensor will automatically collect glucose readings every few minutes, which will be uploaded to the study database at your next clinic visit.

6 final assessments of the first period

at the end of the 16‑week period you will return to the clinic for a final visit.

blood samples will be taken again to measure HbA1c, fasting plasma glucose, and fasting plasma C‑peptide.

your weight, height, waist‑to‑height ratio, and body fat (measured with a calibrated scale) will be recorded.

the data from the continuous glucose monitor will be reviewed to calculate average glucose, time in target range (3.9–10 mmol/l), and any episodes of low glucose.

7 washout period (if applicable)

if a washout interval is required, you will stop receiving any study injections for a short period (typically a few weeks) before beginning the next treatment phase.

8 start of second treatment period (crossover to the other product)

you will begin the second 16‑week period, receiving the product you did not receive in the first period (i.e., if you first received semaglutide, you will now receive the placebo, and vice versa).

the same weekly injection schedule, dose titration, maintenance phase, and monitoring procedures described in steps 2–5 will be repeated.

9 final study visit and completion

after the second 16‑week period you will attend a final clinic visit.

the same set of blood tests, physical measurements, and continuous glucose monitor data collection will be performed as in step 6.

all study data will be compiled to compare the effects of semaglutide versus placebo on your glucose control and other health measures.

Who Can Join the Study?

Be able to give informed consent, meaning you understand the study and agree to take part before any study activities start.
Have diabetes caused by a heterozygous pathogenic or likely pathogenic variant in the HNF1A or HNF4A gene, which means one of your two copies of the gene has a change that can cause disease; this is judged using the ACMG criteria, a set of expert guidelines for classifying gene changes.
Be at least 18 years old.
Have a blood test result called HbA1c of 48 mmol/mol or higher, which shows your average blood sugar over the past few months, or have used insulin (a medicine that lowers blood sugar) at any time in the last 90 days.
Have taken a medication called sulfonylurea (a type of pill that helps lower blood sugar) at any time in the last 90 days.

Who Cannot Join the Study?

Being pregnant, breastfeeding, planning to become pregnant, or not using reliable birth control methods.
Having already taken part in this trial before (previous randomisation).
Having a history of sudden (acute) or long‑lasting (chronic) inflammation of the pancreas, called pancreatitis.
Having very severe liver disease that is at its final stage, known as end‑stage liver disease.
Having a kidney function test (called eGFR) that is less than 15 ml/min/1.73 m², which means the kidneys are working poorly.
Having received treatment for advanced eye disease caused by diabetes, called proliferative retinopathy, within the past 90 days.
Having a known or suspected allergy to the study medication, its inactive ingredients (excipients), or similar products.
Using a medication that mimics the gut hormone GLP‑1, known as a GLP‑1RA, within the past 60 days.
Using a DPP‑4 inhibitor or an SGLT2 inhibitor medication within the past 30 days.
Being unable or unwilling to stop changing doses of certain blood‑sugar medicines (such as sulfonylureas (SU), repaglinide, or mealtime insulin) during the study.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Ofebjx Ulfjalgoha Hatgnbiw	Odense	Denmark
Svodh Dlmwljem Cyzazk Cnobjagvna	Herlev	Denmark

Trial status

Country	Status	Recruitment Start
Denmark	Not yet recruiting	01.09.2026

Trial locations

Investigated Drugs:

Semaglutide

Semaglutide is a medication given by injection under the skin once a week. In this study it is added to the usual sulfonylurea treatment that people with a specific type of diabetes (HNF1A- or HNF4A‑MODY) already take. The purpose of adding semaglutide is to see how well it can lower blood sugar levels when used together with sulfonylurea. Researchers are looking at how much it reduces glucose in the blood and whether it is safe and effective for these patients.

Investigated Diseases:

Monogenic diabetes

HNF1A-MODY – a rare, inherited form of diabetes caused by mutations in the HNF1A gene. It usually becomes apparent in adolescence or early adulthood and is characterized by a gradual increase in blood glucose because the pancreas releases less insulin. Over time the hyperglycemia can become more persistent, often requiring medication to maintain normal levels.
HNF4A-MODY – a rare, genetic type of diabetes resulting from mutations in the HNF4A gene. Symptoms typically emerge in teenage years or young adulthood with a slow rise in blood sugar due to reduced insulin secretion. The disease progresses slowly, and blood‑sugar control may become increasingly difficult, eventually needing pharmacologic management.

Trial ID:

2025-523414-89-00

Trial Phase:

Therapeutic exploratory (Phase II)

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Effect of semaglutide added to sulfonylurea on blood sugar in adults with HNF1A‑MODY and HNF4A‑MODY

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?