Metformin in Psychosis for Weight Gain Prevention (METRIC)
Research type
Research Study
Full title
Metformin in Psychosis for Weight Gain Prevention Trial (METRIC)
IRAS ID
1010474
Contact name
Paul French
Contact email
Sponsor organisation
Pennine Care NHS Foundation Trust
ISRCTN Number
ISRCTN47913690
Research summary
Many people in the UK with psychosis are started on antipsychotic medication to help with their symptoms. However, these drugs can cause a lot of weight gain, which can cause other problems in the future, such as heart disease or diabetes. It also has an impact on how people feel about themselves. Importantly, it may make people want to stop taking their antipsychotic treatment. Metformin is a drug that has been used for over 60 years in the treatment of diabetes. Small studies suggest that it might help stop some of the weight gain caused by antipsychotics and prevent diabetes. This study will look at whether metformin can stop, or reduce, weight gain for people taking antipsychotics in their first episode of psychosis.
The study will involve 340 people who are experiencing psychosis for the first time and have started their antipsychotic medication no longer than a month ago. The study will take place in approximately 15 UK mental health services. Patients will be randomly split into two groups. One group will be asked to take metformin for a year. The other group will be asked to take a placebo. A placebo - also known as a “dummy” or “sham” drug - doesn’t contain any active treatment. METRIC is a blinded trial, meaning that participants and their doctors will not know which drug they are given, until all participants have finished the trial. This is important so we can measure the true effect of metformin by comparing the weight of those taking metformin with those taking placebo.
Participants will be seen by their mental health team every 3 months while taking the drug and for up to 6 months afterwards. We will measure weight, mental health symptoms and how people feel in general about their health. We will also ask if they have been to other services about their psychosis or weight. The risks of metformin are low but we will take some blood tests to make sure that taking the drug is not causing any side effects to patients.
REC name
London - Brighton & Sussex Research Ethics Committee
REC reference
26/LO/0126
Date of REC Opinion
27 Feb 2026
REC opinion
Further Information Favourable Opinion