First 90 days of antipsychotic treatment linked to rapid metabolic changes
pharmafile | October 20, 2026 | News story | | Diabetes, NIHR, Psychiatry, UCL, antipsychotic drugs, diabetes, mental health, mental illness
The first 90 days after starting antipsychotic treatment are a critical period for monitoring blood glucose and weight, according to a study led by University College London (UCL) researchers.
Published in The Lancet Psychiatry and funded by the National Institute for Health and Care Research (NIHR), the observational study analysed NHS GP records for nearly 97,000 adults aged 18–59 in England with severe mental illness who started treatment with olanzapine, quetiapine, risperidone or aripiprazole between 2000 and 2023.
Researchers compared health records covering two years before treatment initiation with those from the following two years. They found that during the first 90 days, glycated haemoglobin (HbA1c), a measure of average blood glucose, rose around 14 times faster and weight around nine times faster than before treatment began.
Olanzapine was associated with the largest early changes among the four medicines studied, with HbA1c rising around 50 times faster and weight around 10 times faster during the first 90 days than in the pre-treatment period.
The findings also highlighted differences in metabolic risk between patient groups. Among those with prediabetes when treatment began, 19% developed type 2 diabetes within two years, compared with 3% of those whose blood glucose was initially normal. Women experienced greater early increases in HbA1c than men.
Importantly, changes in blood glucose and weight did not always occur together, suggesting that monitoring weight alone may fail to identify some metabolic changes.
“However, our study shows that the first 90 days after starting treatment are a key period when changes linked to diabetes and weight gain can begin,” said first author Dr Juan Carlos Bazo-Alvarez, of UCL Epidemiology and Health.
The researchers said healthcare professionals should check both weight and blood glucose before treatment starts and again during the first few months.
The study relied on existing GP records and could not account for all factors affecting metabolic health, including diet, exercise and additional medications. Its observational design also means the findings do not establish that antipsychotic treatment alone caused the changes.
Pic: Artem Podrez
Related Content
Survodutide delivers up to 13.1% weight loss in phase 3 obesity and diabetes trial
Boehringer Ingelheim’s investigational survodutide produced weight loss of up to 13.1% after 76 weeks in …
Study to examine ways of improving diabetes care for younger adults
Researchers at Northumbria University are leading a £1.3m study aimed at helping GP practices improve …
FDA signals support for development of psychedelic therapies in mental healthmental health
The US Food and Drug Administration (FDA) has announced a series of measures aimed at …
