Answers to the questions we get most

6-bromotryptophan (6-BT) is a substance formed when gut bacteria process the amino acid tryptophan from your food. Tryptophan is present in everyday products such as dairy, bananas and eggs. 6-BT is therefore not a foreign drug but a substance everyone has in small amounts in their blood.

No. The study uses a standardised, pharmaceutically produced product with a precisely known dose, manufactured to the standards required for clinical drug research. Standalone 6-BT supplements are not commercially available and we advise against experimenting on your own.

That is not the aim of this study. We are investigating whether 6-BT can slow the decline of your own insulin production. Even if it does, you will still need insulin. More endogenous insulin production does make blood glucose more stable and lowers the long-term risk of complications.

Shortly after diagnosis, some beta cells are still present. That is precisely what we want to protect. In people who have had type 1 diabetes for years, there is usually too little endogenous insulin production left to measure an effect.

The study is funded by BreakthroughT1D (formerly JDRF), an international non-profit for type 1 diabetes research. The researchers have no financial interest in the outcome and the funder has no influence over analysis or publication.

We call you within a week. In that conversation we explain the study and answer your questions. You then receive the written participant information to take home and have at least a week to think it over. Only after you give consent do we schedule a screening visit.

At any time, without giving a reason. You do not owe anyone an explanation and it has no effect whatsoever on your regular care or your relationship with your treating clinician.

That is decided by lot: half the participants receive 6-BT, the other half a placebo. Nobody — not even the researcher — knows who receives which during the study. Which group you were in is revealed only once every participant has completed the study, together with the results.

Travel costs are reimbursed in full and you receive an expense allowance of € 350 for taking part in the study.

No. You keep your usual insulin treatment and your own clinician. The capsules come on top of that. Any changes to your insulin dose are made as usual, in consultation with your own doctor or diabetes nurse.

Yes. Participants come from across the Netherlands. Visits take place at the Clinical Trial Unit at AmsterdamUMC and your travel costs are reimbursed. We schedule visits around your studies or work wherever possible.

Deliberately: this keeps your details between you and the physician-researcher rather than passing through an external form service. The buttons on this site open your own email program with a message already filled in with the questions we need. You decide what to include and what to leave out.

Yes. The study was reviewed and approved by an accredited medical research ethics committee (METC) and is registered in the Dutch national trial register under number NL-OMON58422. Without that approval a study like this cannot start in the Netherlands.

6-BT is a substance the body produces itself. It has already been studied in people: our own BROMO study tested several doses of 6-BT and found it safe and well tolerated. Because this is one of the first studies in people with type 1 diabetes, we cannot fully rule out unknown side effects. That is why we check your blood values at every visit and actively ask about symptoms. Anything we find, we discuss with you.

Your data are pseudonymised: they are given a code, and the key linking that code to you stays in a secure environment within AmsterdamUMC. Researchers work only with the coded data. Processing complies with the GDPR. Published results are never traceable to an individual. Read more in the privacy statement.

If a measurement reveals something relevant to your health, we discuss it with you and — with your consent — with your own clinician.

Alongside the research team, an independent physician is attached to the study, Dr Cohn, who is not involved in running it. You can approach him for advice or questions; his contact details are in the participant information. For complaints you can also contact the AmsterdamUMC complaints officer. See also about us.